JP5145848B2 - Memory device, memory controller and memory system - Google Patents

Description

  The present invention relates to a memory device that records two-dimensional array data such as digital image data, a memory controller of the memory device, and a memory system, and more particularly, effectively reduces the bandwidth that means the number of data that can be processed per unit time. The present invention relates to a memory device, a memory controller, and a memory system.

  Memory devices that record two-dimensionally arranged data such as digital image data are becoming an increasingly large market with the spread of digital broadcasting and video distribution via the Internet. The digital image data is a data group in which pixel gradation information is composed of a plurality of bits (for example, 8 bits, 256 gradations). For example, image data for high-definition broadcasting is image data of 1920 × 1040 pixels per frame. Consists of. The image data in units of frames is arranged in the address space in the image memory according to a predetermined mapping method.

  This memory mapping is determined so that the most efficient access is possible based on the memory configuration and operation of a synchronous DRAM (SDRAM) that is currently popular. For example, an SDRAM has a plurality of banks, each bank has a plurality of word lines and bit lines, a plurality of memory cells at intersections thereof, and a sense amplifier corresponding to the bit lines, and the plurality of banks are independent. Thus, the active operation can be executed. The active operation in the SDRAM is a series of operations for selecting the word line based on the row address and activating the sense amplifier. The SDRAM read operation is a series of operations for outputting the bit line potential amplified by the sense amplifier based on the column address to the input / output terminal as read data. The write operation is input from the input / output terminal. This is a series of operations for inputting the selected write data to the bit line selected based on the column address.

  The address space in the memory in the SDRAM is composed of a plurality of page areas selectable by bank address and row address, and each page area has a bit group or byte group selectable by a column address. The byte group (or bit group) selected by this column address is input / output via a plurality of input / output terminals.

  According to a general mapping method, a pixel of digital image data is associated with each byte (or bit) of a byte group (or bit group) that can be selected by a column address in the page area. Furthermore, according to this mapping method, each bank of the SDRAM can independently execute an active operation and a read or write operation, so that a plurality of page regions associated with the pixel arrangement of the digital image data are The page areas adjacent to the top, bottom, left, and right on the image are arranged so as to correspond to different bank addresses. For example, when the SDRAM has a 4-bank configuration, page areas with bank addresses BA = 0 and 1 are alternately arranged in odd rows, and page areas with bank addresses BA = 2 and 3 are alternately arranged in even rows. . With this arrangement, when reading or writing one frame of image data, it is possible to execute active operation and read or write operation by alternately and temporally overlapping different banks, and unit time The bandwidth, which is the number of pixels that can be processed per hit, can be dramatically increased.

Patent Documents 1 and 2 describe that in a semiconductor memory that stores image data, a plurality of rows can be accessed simultaneously to improve access efficiency.
JP 2001-312885 A Japanese Patent Laid-Open No. 08-180675

  Memory devices that store digital image data, etc. require horizontal access for writing and reading image data in the order of arrangement of matrix pixels, and rectangular access for partial rectangular areas of matrix pixels. become. The horizontal access corresponds to, for example, a raster scan operation in which one frame of image data is written or read by repeating horizontal scanning. In addition, the rectangular access is, for example, an operation of reading out image data of a small rectangular block in an encoding operation such as MPEG to obtain a motion vector, or of reading out image data of a block in image reproduction in a decoding operation. Corresponds to the operation to write.

  However, since the pixel image data is stored in the address space of the memory by the memory mapping described above, there is a problem of effective bandwidth reduction in rectangular access. First, in a page area selected by a bank address and a row address, a byte group, that is, a plurality of bytes (or a plurality of bits) are simultaneously accessed by a column address. However, if the rectangular image area to be accessed in the rectangular access and the plurality of bytes (or a plurality of bits) selected by the column address do not match, useless input / output data is generated in the access by one column address. Secondly, when the rectangular image area to be accessed in the rectangular access and the page area in the address space do not match, it is required to access a plurality of page areas across the boundary of the page area. Control is required.

  The first and second problems are that if the rectangular image area to be accessed does not match the page area and does not match the multiple bytes (or multiple bits) selected by the column address, the memory control is further performed. It becomes complex and causes a reduction in effective bandwidth.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a memory device, a memory controller of the memory device, and a memory system that solve the above-mentioned problems in rectangular access of the memory device.

In order to achieve the above object, according to a first aspect of the present invention, a memory cell array having a plurality of memory unit regions selected by an address;
Multiple input / output terminals;
An input / output unit provided between the memory cell array and a plurality of input / output terminals;
In the memory unit area, a plurality of bytes or bits of data corresponding to the plurality of input / output terminals are stored,
Further, the memory cell array and the input / output unit respond to the first operation code based on the input address and the combination information of the bytes or bits and the first memory unit area corresponding to the input address and A plurality of bytes or bits in the adjacent second memory unit area are accessed, and a plurality of bytes or a combination based on the combination information is obtained from the accessed plurality of bytes or bits in the first and second memory unit areas. A memory device characterized in that a bit is associated with the plurality of input / output terminals.

  According to the first aspect, in response to the first operation code given together with the input address, the memory device can store any combination of multiple bytes (or multiple bits) based on the input address and the combination information. Since data can be input and output at the same time, it is possible to avoid a decrease in effective bandwidth in rectangular access that crosses the boundary of the memory unit area.

  In order to achieve the above object, according to a second aspect of the present invention, a memory system includes a memory device according to the first aspect, the address, the byte or the bit together with the first operation code. And a memory controller for supplying combination information to the memory device and accessing a plurality of bytes or bits in the first and second memory unit areas in the memory device.

  In order to achieve the above object, according to a third aspect of the present invention, in a memory controller for controlling a memory device according to the first aspect, together with the first operation code, the address and the byte or bit. The combination information is supplied to the memory device, and a plurality of bytes or bits in the first and second memory unit areas in the memory device are accessed.

  Even if the area to be accessed for the memory device exceeds the memory unit area selected by the input address, a plurality of bytes in any combination in two adjacent memory unit areas using byte or bit combination information Or the bits can be accessed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but extends to the matters described in the claims and equivalents thereof.

[Memory mapping and problems of image memory]
FIG. 1 is a diagram showing memory mapping of the image memory in the present embodiment. In FIG. 1, display image data in an image processing system including the display device 10 is stored in an image memory 15. The display image data is composed of data such as a luminance signal Y and color difference signals Ca and Cb of each pixel and an RGB gradation signal of each pixel, and each signal is composed of, for example, 8-bit (1 byte) data.

  On the other hand, the image memory 15 is generally composed of a large-capacity and high-speed semiconductor memory device in which an integrated circuit is formed on a semiconductor substrate such as SDRAM. Such an image memory is composed of a plurality of banks Bank 0 to 3 (four banks in FIG. 1), each bank Bank 0 has a plurality of blocks BLK-0, and each block has a plurality of word lines WL and bit lines. It has BL and memory cell MC at the intersection. Although not shown, the memory cell includes a MOS transistor having a gate connected to a word line and a capacitor connected to the transistor. In the example of FIG. 1, four banks are associated with bank addresses BA0-BA3, word lines are associated with row addresses RA0-RA7, and bit lines are associated with column addresses CA0-CA127. A word line in the bank which is a combination of the bank address BA and the row address RA is selected, and a bit line is selected by the column address CA. The 4-byte data BY0-3 is accessed by the bank address BA, row address RA, and column address CA. Since one byte is composed of 8 bits, data of 4 bytes, that is, 4 × 8 = 32 bits, is read or written in association with the input / output terminal of the memory in one access. In general, the 1-byte data (8-bit data) corresponds to a pixel signal. By inputting / outputting 4-byte data in one access, the bandwidth, which means the number of pixels that can be processed per unit time for the image memory, can be increased.

  According to the memory mapping 12 for the display image data, the page area 14 specified by the bank address BA and the row address RA is arranged in a matrix. One page area 14 has 128 memory unit areas specified by column addresses CA0-127 as shown in the enlarged area 14E, and each memory unit area stores 4-byte data BY0-3. . The 4-byte data BY0-3 is input / output via a total of 32 input / output terminals, ie, memory input / output terminals DQ0-7, DQ8-15, DQ16-23, and DQ24-31. The 8-bit data of each byte corresponds to the pixel signal data.

  The memory mapping 12 is suitable for operating the image memory 15 such as SDRAM having a plurality of banks at high speed. The SDRAM drives the selected word line in the selected bank in response to an active command given together with the bank address BA and the row address RA, reads the memory cell data to the bit line, and associates it with the bit line. An active operation for activating the sense amplifier and amplifying the bit line potential is performed, and then a read operation for reading data from the selected bit line is performed in response to a read command given together with the column address CA. Alternatively, the SDRAM performs a write operation for writing the write data to the selected bit line in response to a write command given together with the column address CA and the write data after the active operation. After the read operation or write operation, a precharge operation by a precharge command is performed, and the active operation, read operation, or write operation is performed again. As described above, in the SDRAM, each bank can independently perform an active operation, a read operation, and a write operation.

  According to the memory mapping 12 of FIG. 1, different bank addresses BA0-3 are associated with page areas 14 that are adjacent vertically and horizontally. That is, bank addresses BA0, 1 are alternately arranged in odd rows of the memory mapping 12, and bank addresses BA2, 3 are alternately arranged in even rows. Further, in the raster direction (row direction) of the memory mapping 12, the row address RA0-7 is incremented while being repeated two by two, and each row of the memory mapping 12 is folded at four row addresses RA0-3 and RA4-7. Yes.

  In this way, if memory mapping is used in which the page area on the image is allocated so that the page area of the same bank is not adjacent in either the row direction or the column direction on the memory, a typical access to the image memory is possible. In a certain horizontal access, that is, an access in which the page area 14 is moved and selected in the row direction, the access can be performed while simultaneously executing the active operation and the read / write operation in two banks, and the access efficiency can be improved. . The same applies to access in the vertical direction.

  FIG. 2 is a diagram showing two accesses in the image memory. The horizontal access shown in FIG. 2A is an access that frequently occurs when inputting and outputting a video frame image, and corresponds to a raster scan in which the image is accessed in the horizontal direction 20 from the upper left to the lower right. On the other hand, the rectangular access in FIG. 2B is an access that frequently occurs in image compression and decompression processing such as MPEG, and is accessed as indicated by the arrow 24 from the upper left to the lower right in the rectangle 22 having an arbitrary aspect ratio. It corresponds to the operation. The rectangular area 22 corresponds to an MPEG motion vector extraction target block or the like.

  In general, in an image system using an image memory, the transfer rate of the image memory, which is a frame memory, is set faster than the screen display operation, and image data read out by horizontal access of the image memory is displayed on the screen. New frame data is created by rectangular access, and frame data can be created and output without interruption. For this reason, in an actual image system, horizontal access and rectangular access are mixed.

  In the horizontal access, since scanning is performed in the horizontal direction 20, memory access can be efficiently performed while simultaneously activating adjacent banks. On the other hand, in the rectangular access, the bank address BA and the row address RA are obtained by preventing the position of the accessed rectangular area 22 from exceeding a single bank and further from exceeding the page area in the bank. Since the data in the rectangular area 22 can be accessed by one designated active operation, efficient memory access can be performed in the same way as horizontal access.

  FIG. 3 is a diagram illustrating a problem of horizontal access. A horizontal access timing chart 30 for accessing the horizontal direction 20 in the memory map 12 is shown. In this timing chart, when the page area (BA0 / RA4, BA1 / RA4, BA0 / RA5, BA1 / RA5) in the fourth row of the memory map 12 is accessed horizontally (20 in the figure), the automatic refresh command AREF is It has occurred. The timing chart 30 shows a command CMD, a clock CLK, a bank address BA, a row address RA, a column address CA, and an input / output terminal DQ.

  As a premise, the burst length BL is set to 4. When the page area of BA0 / RA4 is activated by the active command ACT32 and reading of BA0 / CA0 is instructed by the read command RD33, four sets of 32-bit data are input / output after a predetermined latency (4 clocks in the figure). It is continuously output from the terminal DQ in 4 clock cycles. That is, four sets of 32-bit data at column addresses CA0 to CA3 in the page area BA0 / RA4 are continuously output in four steps. This burst operation is an operation in which SDRAM is required by the standard. This means that each 4-byte (32-bit) data of the column addresses CA0 to CA3 in the enlarged page area 14E in FIG.

  Next, 4-byte data of the page area BA1 / RA4 is output by the active command ACT34 and the read command RD35. Similarly, 4-byte data of page area BA0 / RA5 is output by active command ACT36 and read command RD37, and 4-byte data of page area BA1 / RA5 is output by active command ACT38 and read command RD39, respectively.

  At this time, when an automatic refresh command AREF 40 for designating the row address RA6 is generated, the SDRAM memory constituting the image memory executes the refresh operation in parallel in all the built-in banks, the four banks BA0-3. That is, the word lines of the row address RA6 in the four banks are simultaneously driven, the sense amplifier is activated, rewriting is performed, and a precharge operation is performed. This refresh operation means that the four page areas 31 in the memory map 12 in FIG. 3 are performed. Therefore, the horizontal access (arrow 20) is temporarily stopped during the refresh operation period tREF. Then, after the refresh operation period tREF, the horizontal access is resumed by accessing the next page area BA0 / RA6 again with the active command ACT41 and the read command RD (not shown).

  Since the refresh operation by the automatic refresh command AREF is performed at the same time for four banks, if a refresh command is generated during horizontal access, the horizontal access is temporarily interrupted and the effective bandwidth is narrowed. This is a problem in horizontal access.

  FIG. 4 is a diagram illustrating a first problem of rectangular access. FIG. 4A shows an example of horizontal access, and FIG. 4B shows an example of rectangular access. In either case, the access exceeds the boundary of the memory unit area (4-byte area) 45 selected by the column address CA. As described above, according to a general memory map, the page area 14 specified by the bank address BA and the row address RA is divided into a plurality of memory unit areas 45 selected by the column addresses CA0-127. Data of 4 bytes BY0-3 are simultaneously accessed by two column addresses CA. The 8-bit data of each byte corresponds to the pixel signal.

  For this reason, access is performed with relatively little waste in horizontal access, but wasteful data input / output occurs in rectangular access, and the effective bandwidth is reduced.

  In the horizontal access shown in FIG. 4A, when the area 22A is accessed, four read commands RD are issued for the column address CA0-3 following the active command ACT designating the page area BA0 / RA0, and the column address CA0. -3, 4-byte data BY0-3 is input / output continuously. In this case, since the area 22A includes the bytes BY2 and 3 of the column address CA0 to the bytes BY0 and 1 of the column address CA3, the data of the bytes BY0 and 1 of the 4-byte input / output DQ corresponding to the column address CA0. Is not required, and the data of bytes BY2 and 3 among the 4-byte input / output DQ corresponding to the column address CA3 is not required. Therefore, the valid output data is 12 bytes / 16 bytes.

  On the other hand, in the rectangular access shown in FIG. 4B, when the rectangular area 22B is accessed, the six read commands RD are added to the column addresses CA0, 1, following the active command ACT specifying the page area BA0 / RA0. 4, 5, 8, 9 are issued, and 4-byte data BY 0-3 of the column addresses CA 0, 1, 4, 5, 8, 9 is input / output continuously. However, since the rectangular area 22B does not coincide with the boundary of the memory unit area (4-byte area) 45 selected by the column address and exceeds the boundary of the 4-byte area, each of the 4-byte data BY0-3 is half. Becomes unnecessary data. That is, valid output data is 12 bytes / 24 bytes. FIG. 4B shows the worst case.

  As described above, even in the case of data of the same number of bytes, the above rectangular access needs to input / output 24 bytes of data by six read commands RD, but in horizontal access, four read commands RD. Therefore, it is sufficient to input / output 16 bytes of data. Therefore, an effective bandwidth decreases when accessing a rectangular area exceeding the boundary of the 4-byte area (memory unit area) 45 selected by one column address. This is the first problem of rectangular access.

  FIG. 5 is a diagram illustrating a second problem of rectangular access. The rectangular access is an access to an arbitrary rectangular area, and the rectangular area may exceed the boundary 14BOU of the adjacent page area 14. In FIG. 5, the rectangular area 22 (A) is a 16-byte area in the same page area BA1 / RA6, and the rectangular area 22 (B) is four adjacent page areas BA3 / RA2, BA2 / RA3, BA1 /. A case of a 16-byte area extending over RA6, BA0 / RA7 is shown.

  In the case of the rectangular area 22 (A), as shown in the timing chart, one active command ACT (50 in the figure) for the page area BA1 / RA6 and four times for the column addresses CA6, 7, 10, 11 are shown. 16 bytes of data can be input / output by issuing a read command RD (52 in the figure).

  On the other hand, in the case of the rectangular area 22 (B), as shown in the timing chart, four active commands ACT (54 in the figure) for the page areas BA3 / RA2, BA2 / RA3, BA1 / RA6, BA0 / RA7 and 16-byte data cannot be input / output unless four read commands RD (56 in the figure) are issued for column addresses CA127 (BA3), CA124 (BA2), CA3 (BA1), and CA0 (BA0). That is, when the rectangular area 22 includes adjacent page areas, the active command ACT is issued a plurality of times to activate different banks, and the read RD or write command WR is issued with the column address in each bank. Must. Therefore, the amount of data that can be accessed per unit time is reduced, and the effective bandwidth is reduced.

  When the rectangular area 22 (B) in FIG. 5 is partitioned in the middle of the memory unit area (4-byte area) selected by the column address, the first problem shown in FIG. In addition to requiring multiple active commands (second problem), unnecessary data is included in the input / output data DQ for the read command (first problem). Resulting in lower bandwidth.

  As described above, when memory mapping utilizing the structural characteristics of the SDRAM is adopted in the image memory, the first problem is that access is interrupted by the occurrence of a refresh command during horizontal access, and the second is that the rectangular access area is a column. The problem that input / output data is wasted when the boundary of the memory unit area (4-byte area) selected by the address is exceeded. Third, when the rectangular access area exceeds the boundary of the page area specified by the bank address There is a problem that it is necessary to issue a plurality of bank active commands.

[Overview of this embodiment]
Below, the structure and operation | movement which solves those subjects are demonstrated roughly.

  In this embodiment, access interruption caused by refresh operation and access efficiency decrease due to rectangular access are solved. First, refresh operation can be performed in the background in parallel with access operation during horizontal access. Second, it enables a function to efficiently access an area shifted from the memory unit area (4-byte area) selected by the column address at the time of rectangular access or an area exceeding the memory unit area. This enables a function for efficiently accessing a rectangular area including a plurality of page areas across the boundary of the page area at the time of rectangular access.

  FIG. 6 is a diagram showing the overall operation in the present embodiment. As described above, in an image system using an image memory, horizontal access and rectangular access to the image memory occur together. In the example of FIG. 6, the horizontal access 20-1 for the page area of the bank address BA0, BA1 in the first row of the memory map 12, the rectangular access 22 for the page area BA2 / RA2 in the second row, and the bank in the second row. This is an example in which horizontal access 20-2 to the page areas of addresses BA2 and BA3 occurs in order. In the rectangular access 22, an access is made to a rectangular area that exceeds the boundary of the memory unit area (4-byte area) 45 in one page area BA2 / RA2.

  In this case, in the rectangular access, an access is made to an arbitrary bank of the memory, but in the horizontal access, the access is made only to a predetermined bank for a certain period. For example, during the horizontal access of the first row in the memory map 12, only the bank BA0, 1 is accessed, and the bank BA2, 3 of the second row is not accessed. Conversely, during horizontal access on the second row, access occurs only in the banks BA2 and BA3, and access does not occur in the banks BA0 and BA1 on the first row.

  Therefore, in the horizontal access 20-1, before entering the memory access, a background refresh command BREN for designating a bank that will not be accessed for a while will be issued, and bank information SA = 2/3 that will not be accessed is stored in the memory. Notify That is, a subsequent automatic refresh operation is permitted to the bank SA designated by the background refresh command BREN. Therefore, normal access to the banks SA = 2 and 3 designated for the refresh operation is prohibited.

  In the horizontal access 20-1 in FIG. 6, refresh bank information SA (61 in the figure) for permitting the subsequent refresh operation is issued together with the background refresh command BREN (60 in the figure), and then the page area by the active command ACT. BA0 / RA0 is activated and 4-byte data BY0-3 of column address CA0 is output to input / output terminal DQ by read command RD (BA0, CA0). Similarly, page area BA1 / RA0 is activated by active command ACT, and 4-byte data BY0-3 of column address CA0 is output to input / output terminal DQ by read command RD (BA1, CA0). However, in FIG. 6, the output of four sets of 4-byte data corresponding to BL = 4 is omitted.

  When an automatic refresh request (not shown) is issued in the image memory during the horizontal access 20-1 and is traced to the background refresh command BREN, the refresh operation for the banks BA2 and BA3 is started. The However, the horizontal access only causes access to the banks BA0 and BA1, and different banks can be independently activated in the SDRAM, so the horizontal access is disturbed and interrupted by the refresh operation in the banks BA2 and BA3. There is nothing.

  Next, in the rectangular access of FIG. 6, the rectangular area 22 is in the same page area BA2 / RA2, and the latter two bytes BY2, 3 in the column address CA0 and the first two bytes BY0, 1 in the column address CA1. Including. In this case, according to a general read command of SDRAM, it is necessary to issue two read commands RD to the column addresses CA0, CA1.

  However, in this embodiment, by issuing a read command RD (62 in the figure) for the column address CA0 (63 in the figure) and supplying byte combination information SB (64 in the figure) for the access, the byte combination Four bytes corresponding to the information SB can be automatically associated with the input / output terminal DQ. In the above example, by specifying byte shift information SB = 2 to be shifted by 2 bytes as the byte combination information SB, among the 4 byte data of the column address CA0, the data of bytes BY2 and 3 shifted by 2 bytes and the adjacent data Of the 4-byte data at the column address CA1, the first 2-byte bytes BY0, 1 are automatically output.

  In the rectangular access in FIG. 6, following the active command ACT for the page area BA2 / RA2, a read command RD62 designating BA2 / CA0 (63 in the figure) is issued together with the byte combination information SB = 2 (64 in the figure). . This byte combination information SB = 2 means a combination of 4-byte data from the byte BY2 shifted by 2 bytes in the 4-byte area. Alternatively, this byte combination information SB = 2 means that the first byte position (start byte) in the 4-byte area is BY2. In response to this, the image memory stores the data of the bytes BY2 and 3 shifted by 2 bytes (or from the start byte BY2) and the byte data BY0 and 1 of the column address CA1 among the 4-byte data of the column address CA0. Data is output in correspondence with the 4-byte input / output terminal DQ. The memory controller does not need to issue the read command RD for the column addresses CA0, CA twice. Moreover, only necessary data is output to the 4-byte input / output terminals DQ, and unnecessary data is not output, resulting in high access efficiency.

  Further, when the read command RD for specifying BA2 / CA4 is issued together with the combination information SB = 2, the image memory outputs 4-byte data consisting of 2 bytes in the column addresses CA4 and 5 and specifies BA2 / CA8. When the read command RD to be issued is issued together with the combination information SB = 2, 4-byte data consisting of 2 bytes each in the column addresses CA8 and 9 is output, and the read command RD for specifying BA2 / CA12 is output together with the combination information SB = 2 When issued, 4-byte data consisting of 2 bytes each in the column addresses CA12 and CA13 is output.

  As a result, even if the rectangular access area 22 includes the memory unit areas (4-byte areas) of the eight column addresses CA0, 1, 4, 5, 8, 9, 12, and 13, the read command RD receives the column address CA0. , 4, 8, and 12 are only required to be issued four times, and there is no unnecessary data output at the input / output terminals, and the access efficiency can be doubled.

  Since the horizontal access 20-2 after the rectangular access is an access to the page area of the second row of the memory map 12, the normal access to the banks BA0 and BA1 does not occur for the time being. Therefore, similarly to the above, SA = 0/1 is designated as the bank information SA (66 in the figure) permitting the refresh operation together with the background refresh command BREN (65 in the figure), and the subsequent bank BA2 and 3 are transferred to the banks BA2 and BA3. In parallel with the normal access, an automatic refresh operation to the banks BA0 and BA1 is permitted.

  As described above, in the horizontal accesses 20-1 and 20-2, automatic refresh in the background is permitted during normal access, and in the rectangular access, automatic refresh in the background is not permitted. As a result, in the horizontal access 20-1, a normal access operation in the banks BA0, 1 and a refresh operation in the banks BA2, 3 are possible in parallel, and in the horizontal access 20-2, a normal access operation in the banks BA2, 3. Refresh operations can be performed in parallel in banks BA0 and BA1. As a result, horizontal access disturbance due to the refresh operation can be avoided, and an effective reduction in bandwidth can be suppressed.

  In rectangular access, the background refresh operation is prohibited. Thereby, rectangular access to an arbitrary area can be prevented from being interrupted by the refresh operation. Therefore, a decrease in total effective bandwidth can be suppressed.

  In the rectangular access, the byte combination information SB is specified together with the read command, and the combined byte data is input to the 4-byte input / output terminal DQ with any byte combination starting from the column address CA of the read command. Can be output. The byte combination information SB can be specified together with a command for setting the mode register prior to the active command.

  FIG. 7 is a diagram showing another example of the overall operation in the present embodiment. In this example, horizontal access 20-1 to the page area of the first row of the memory map, rectangular access 22, and horizontal access 20-2 to the page area of the second row of the memory map are sequentially performed. is there. In the rectangular access 22, the rectangular area 22 exceeds the page area boundary 14BOU, and is divided into four page areas BA3 / RA2, BA2 / RA3, BA1 / RA6. Includes BA0 / RA7.

  In the horizontal accesses 20-1 and 20-2, as in FIG. 6, by issuing the refresh bank information SA together with the background refresh command BREN, the subsequent automatic refresh operation to the bank is permitted, and the horizontal access is performed. Is prevented from being disturbed by the refresh operation. In rectangular access to a rectangular area 22 including a plurality of page areas, that is, a plurality of banks, multi-bank information SA ′ is issued together with an acti command ACT as bank information to be simultaneously activated. In response to this, the image memory simultaneously performs an active operation on the page areas of a plurality of banks designated by the multi-bank information SA ′ with the address information BA and RA issued together with the active command ACT as the upper left. As a result, in response to one active command ACT, a plurality of banks can be activated simultaneously, and thereafter, a read command RD for each bank is issued together with a bank address BA and a column address CA, whereby each bank 4 bank data of the memory unit area (4 bank area) selected by the column address CA can be output to the input / output terminal DQ.

  In the example of rectangular access in FIG. 7, address information BA3 and RA2 (71 in the figure) specifying the upper left page area are issued together with the active command ACT (70 in the figure), and at the same time, the multibank information SA ′ = 0− 3 (72 in the figure) is also issued. In response to this, the image memory simultaneously activates the four banks BA3, BA2, BA1, BA0 designated by the multibank information SA ′ with the bank BA3 in the upper left page area as the head, and the subsequent four The 4-byte data of the bank BA / column address CA specified by the read command RD is output in order. The same applies to the write command. In the figure, BA3 / CA127, BA2 / CA124, BA1 / CA3, BA0 / CA0 are supplied to four read commands RD, and 4-byte data of each is output.

  If the multi-bank information SA ′ is “2 banks in the horizontal direction”, the bank on the right of the upper left bank corresponding to the bank address BA supplied by the active command ACT is also activated at the same time. If so, the banks below the upper left bank are simultaneously activated. Similarly, if the multi-bank information SA 'is "4 banks vertically and horizontally", the four banks adjacent to the right, bottom, and bottom right of the upper left bank are simultaneously activated. Therefore, in order to automatically activate the multibank, how the row address RA of each row of the memory map is arranged, specifically, in what unit the row address RA is folded back to each row It is preferable to set information (row address step information) in a register or the like in advance.

  In the rectangular access of FIG. 7, when the byte combination information SB described in FIG. 6 is specified together with the read command RD in addition to the multi-bank information SA ′ at the time of the active command ACT, the boundary 14BOU of the page area 14 is exceeded, In addition, some byte combinations in the memory unit area (four bank area) selected by the column address CA can be automatically associated with the input / output terminal DQ.

  FIG. 8 is a configuration diagram of the image processing system in the present embodiment. The image processing system includes an image processing chip 80 corresponding to a memory controller and an image memory chip 86 that stores image data to be processed. The image processing chip 80 and the memory chip 86 are semiconductor chips, and an integrated circuit is formed on each single semiconductor substrate.

  The image processing chip 80 responds to a memory access request including an image processing control unit 81 that performs image processing, such as an encoder and a decoder corresponding to MPEG image compression and decompression, and an image area designation from the image processing control unit 81. And a memory control unit 82 for controlling access to the image memory chip 86. The memory control unit 82 includes a background refresh control unit 84 that controls the background refresh operation in horizontal access, and a byte boundary that controls access to any combination of bytes in the memory unit area (4-byte area) through rectangular access. It has a control unit 85 and a multi-bank activation control unit 83 that controls access including a plurality of page areas by rectangular access. With these controls, commands and bank addresses, row addresses, column addresses, byte combination information SB, refresh bank information SA, multi-bank information SA ′, and the like necessary for each operation are issued to the image memory 86.

  The image memory 86 has a plurality of banks Bank 0 to 3 in the memory core 92, and controls the row control unit 87 that mainly controls the active operation and the read and write operations for these memory cores 92. A column control unit 90 to perform and a background refresh control unit 89 are provided. The row controller 87 has a multi-bank activation controller 88, and the column controller 90 has a byte boundary controller 91. Each bank Bank0-3 includes a row decoder RowDec, a column decoder ColDec, a memory array MA, a sense amplifier group SA, an input / output unit 93 for associating the memory array MA and an input / output terminal DQ. It is.

  FIG. 9 is a configuration diagram of the image memory in the present embodiment. In the image memory chip 86, the external terminal group 93 includes a command terminal including RAS, CAS, WE, and CS, bank address terminals BA0 and BA1, refresh bank information terminals SA0 and SA1, and a plurality of addresses in addition to the clock CLK. A terminal Add, a byte combination information terminal SB having a predetermined number of bits, a data input / output terminal DQ having a predetermined number of bits, a multi-bank information terminal SA ′ not shown, and the like are included.

  Note that the terminals SB, SA ', and SA required for the aforementioned byte boundary function, multi-bank access function, and background refresh function can also be realized by a common special pin. Since such information is supplied together with different commands, the special pin input data may be set in the corresponding register in accordance with the supplied command.

  Further, these terminals SB, SA ', and SA can be realized by unused terminals. For example, in the read operation, if the row address is input at the address terminals Add0 to 12 and the column address is input at the address terminals Add0 to 9, the address terminals Add10 to 12 are not used when the column address is input. . Therefore, the control data SB, SA ′, SA can be input from the address terminals Add10 to 12 that are not used when the column address is input.

  Each of these external terminal groups 93 is connected to an internal circuit via a buffer 94. The command group is input to the command control unit 95, and a control signal corresponding to the command is supplied to the internal circuit. In response to the mode register set command, the command control unit 95 sets a predetermined setting value in the mode register 96 based on the setting data supplied to the address pin Add. The setting information set in the mode register 96 is supplied to the internal circuit. The row control unit 87 includes a multi-bank activation control unit 88, and further includes a row address calculation unit 97 necessary for multi-bank activation. From the multi-bank activation control unit 88, an active pulse is supplied to the bank to be activated. The row address calculation unit 97 supplies a row address to be activated to each bank. In the bank Bank, a refresh row address instructing unit 98 for instructing a row address to be refreshed in the bank is provided. The refresh row address instruction unit 98 has a refresh counter, for example, and generates a row address necessary when an automatic refresh command is generated. The configuration in the bank is as described above.

Hereinafter, the details of the image memory and the memory controller will be described in order for the byte boundary function, the multi-bank active function, and the background refresh function described with reference to FIGS.
《Byte Boundary》
FIG. 10 is a diagram for explaining the byte boundary functions. This figure shows a byte group (or bit group) selected by a row address RA and a column address CA in a certain bank. As described above, also in this example, a 4-byte data area (memory unit area) is selected by the row address RA and the column address CA, and is associated with the 32-bit input / output terminals DQ0-31. Therefore, “0123” at the intersection of the row address RA and the column address CA means the bytes BY0, BY1, BY2, and BY3, respectively. Alternatively, 4 bits may be used instead of 4 bytes. In this case, a 4-bit data area (memory unit area) is selected by the row address RA and the column address CA, and is associated with the 4-bit input / output terminals DQ0-3. The following is an example of 4 bytes for simplicity.

  FIG. 10A corresponds to the conventional example, and a 4-byte data area is uniquely determined by the row address RA and the column address CA, and 32 bits of the 4-byte area (memory unit area) 100 and 101 are always input / output. Associated with terminals DQ0-31.

  On the other hand, FIG. 10B corresponds to the present embodiment, and the input / output terminals DQ0-31 are combined with arbitrary bytes, starting with a 4-byte area specified by the row address RA and the column address CA. Can be associated with In the figure, all 4-byte areas 100 selected when RA = 0 and CA = 0 are directly associated with the input / output terminals DQ0-31. On the other hand, the 4-byte area 102 continuous from the third byte shifted by 2 bytes in the 4-byte area selected by RA = 2 and CA = 1 is associated with the input / output terminals DQ0-31. In this case, the first information (start byte) indicating which byte in the 4-byte area selected by RA = 2 and CA = 1 is the head, and whether 4 bytes are continuous or down from the head byte. Second information (big endian or little endian) such as whether 4 bytes are continuous in the direction, every other one in the up direction or every other one in the down direction is given together with the read command and the write command.

  Based on the byte combination information consisting of the first and second information, the input / output unit of the image memory extracts a total of 4 bytes from the byte data corresponding to different column addresses CA in the page, Associated with input / output terminals DQ0-31. Then, necessary 4-byte data is input / output from the 32-bit input / output terminal DQ at a time.

  FIG. 11 is a diagram showing a timing chart in the byte boundary function. In this example, 4 bytes 102 in the memory map 12 are accessed. First, the bank address BA = 0 and the row address RA = 2 are given together with the active command ACT (110 in the figure), the corresponding page area is activated, and the bank address BA = 0 along with the read command RD (111 in the figure). And column address CA = 1 (112 in the figure), and further, as the byte combination information 113, the first information SB = 2 (114 in the figure) indicating the byte shift amount or the start byte and the combination pattern are shown. Second information BMR = UP (115 in the figure) is given.

  Based on the byte combination information SB = 2 and BMR = UP, the image memory uses the latter half of the 4-byte area selected by the column address CA = 1 (BY2, 3) and the column address CA = 2. The first half of the selected 4-byte area (BY0, 1) is associated with the input / output terminals DQ16-23, DQ24-31, DQ0-7, and DQ8-15 as shown in the figure. This association is performed in the input / output unit 93 by the byte boundary control unit 91 of FIG. Therefore, in spite of the data of different column addresses, any combination of 4-byte data can be associated with the input / output terminal DQ by giving the read command RD once. The same applies to the write command.

  In FIG. 11, the same byte boundary function can be applied even if the 4-byte area selected by the row address RA and the column address CA is a 4-bit area. In this case, 4-bit data in a 4-bit area is associated with the input / output terminals DQ0-3.

  FIG. 12 is a diagram for explaining the byte boundary functions for different mappings. In FIG. 12, for the sake of simplicity, the memory unit area selected by the row address RA and the column address CA is composed of 4 bits. In the left side of FIG. 12, memory mappings 12-1 and 12-2 indicating the correspondence between image pixels and memory spaces are shown, in the center are memory logical spaces 15-1 and 15-2, and on the right side are memory mappings 12-1 and 15-2. A timing chart corresponding to is shown.

  In the central memory logical spaces 15-1 and 15-2, "0-3" indicating 4 bits in the 4-bit area selected by the row address RA and the column address CA is shown, and the input / output terminal DQ0 -3. Also in the left memory mappings 12-1 and 12-2, “0-3” indicating 4 bits in the memory logical space corresponding to the image pixels is shown. That is, the memory mapping shows how each pixel of the image is associated with the input / output terminals DQ0-3 of the memory.

  In the image system, it is up to the system designer to associate the image pixels with any of the 4-bit input / output terminals DQ0-3 that are simultaneously accessed at a certain address BA, RA, CA. Mapping 12-1 is an example of mapping four pixels from left to right in the figure to input / output terminals DQ0-3 in the same direction as the address moving direction (left to right), and is called big endian. On the other hand, the mapping 12-2 is an example in which four pixels are mapped to the input / output terminals DQ3-0 in the direction opposite to the address traveling direction, and is called little endian.

  In both mappings 12-1 and 12-2, rectangular access occurs in the four pixels 123 and 127 from 6 pixels to 9 pixels from the upper left corner of the image. However, since these mappings are mapped in the opposite direction to the 4 bits in the memory, different accesses are required. That is, in the case of the mapping 12-1, as indicated by the arrow 120, for the pixels from the left to the right of the image, DQ1, CA = 1, DQ2, CA = 1, DQ2, CA = 1, DQ3, CA = It is necessary to input / output data in the order of DQ0 in 2. On the other hand, in the case of the mapping 12-2, as indicated by an arrow 124, DQ 2 in CA = 1, DQ 1 in CA = 1, DQ 0 in CA = 1, CA = It is necessary to input / output data in the order of DQ3 in 2.

  Bit combination information SB and BMR are used to cope with such different mappings. That is, in the case of the mapping 12-1, as shown at 121 in the figure, the read command RD and the head address consisting of BA = 0 and CA = 1 and the bit combination information consisting of SB = 1 and BMR = UP are issued. In response, as shown at 122 in the figure, CA = 1 3-bit DQ1, 2, 3 and CA = 2 DQ0 are output simultaneously.

  On the other hand, in the case of mapping 12-2, as shown by 125 in the figure, a read command RD and a head address consisting of BA = 0, CA = 1 and bit combination information consisting of SB = 1, BMR = DOWN are issued. In response to this, 3 bits DQ0, 1, 2 with CA = 1 and DQ3 with CA = 2 are output at the same time as 126 in the figure.

  Thus, by specifying the bit combination information SB and BMR corresponding to different memory mappings of big endian and little endian, the image memory can input and output 4 bits simultaneously corresponding to the memory mapping on the system side. it can. By increasing the types of bit combination information, flexible 4-bit access can be realized for various mappings.

  FIG. 13 is a diagram for explaining the big endian and the little endian in FIG. 12. FIG. 13 shows an image processing system that uses a memory with an input / output bit width of 4 bits on both the left and right sides. The right is a little endian system that handles the direction from DQ3 to DQ0 of the memory DQ as the forward direction.

  The pixel positions (X0 to X11) on the screen both indicate physical positions on the same screen. The “pixel information” at each pixel position is the same “A” to “L” in both systems, which means that both systems display the same image. ing.

  In big-endian systems, pixel positions X0 to X3 are assigned to DQ0 to DQ3 at memory address CA0, pixel positions X4 to X7 are assigned to DQ0 to DQ3 at memory address CA1, and pixel positions X8 to X11 are assigned to DQ0 at memory address CA2. It corresponds to ~ DQ3.

  On the other hand, in the little endian system, pixel positions X0 to X3 are assigned to DQ3 to DQ0 of memory address CA0, pixel positions X4 to X7 are assigned to DQ3 to DQ0 of memory address CA1, and pixel positions X8 to X11 are assigned to memory address CA2. It corresponds to DQ3-DQ0.

  That is, when both systems are compared, the correspondence between the pixels X0 to X3 and the input / output terminals T0 to T3 in the image processing system is opposite between big endian and little endian. Therefore, the pixel information “A” at the pixel position X0 is stored in different physical positions (DQ0 of CA0 and DQ3 of CA0) in the big-endian system and the little-endian system.

  Here, when the image processing system generates a rectangular access (130 in the figure) for the pixel information “FGHI” at the pixel positions X5 to X8, the memory is a physical memory of different memory cells in the big endian system and the little endian system. Locations 132 and 134 must be accessed. Therefore, the minimum information that needs to be supplied to the memory is information BMR indicating whether the system is big-endian (Up) or little-endian (Down), the address CA containing the starting bit, and the starting bit. Of the location information SB in the address of.

  The big endian and the little endian are the same when the memory unit area accessed by the addresses RA and CA is a 4-byte area (byte group). FIG. 14 is a diagram for explaining a byte boundary function in special memory mapping. FIG. 14 also shows the memory mapping 12 on the left side, the memory logical space 15 on the center, and the corresponding timing chart on the right side as in FIG.

  In the figure, the memory mapping 12 on the left shows the state of which bits of the memory are assigned to each pixel in the frame image. In this example, one pixel is composed of 2-bit information. For example, even bits hold data representing luminance and odd bits hold data representing color difference.

Therefore, Grouping-1 is a rectangular access that collects only luminance information (even bits) in the second to fifth pixels in the upper left corner, and Grouping-2 is color difference information (odd numbers) in the second to fifth pixels in the upper left corner. Means a rectangular access that only collects bits). In this case, both Grouping-1 / 2 are rectangular accesses from the second pixel to the fifth pixel in the upper left corner of the image, but the luminance (even bit) as indicated by arrow 140 and the color difference (odd bit) as indicated by arrow 144 Due to the difference, as shown in the timing chart, the access from the image processing system to the memory and the input / output terminal DQ are as follows.
Grouping-1: For CA = 0 / SB = 2 and access of BMR = AL (designation of collecting 4 bits every other bit) (141 in the figure), CA = 1 is applied to the input / output terminals DQ0-3. DQ0, CA = 2 DQ0, CA = 0 DQ2, and CA = 1 DQ2 are associated (142 in the figure).
Grouping-2: For CA = 0 / SB = 3 and BMR = AL (designation to collect 4 bits every other bit) (145 in the figure), CA = 2 for I / O terminals DQ0-3 DQ1, CA = 1 DQ1, 3 and CA = 0 DQ3 are associated (146 in the figure).

  In this way, since the same DQ (for example, DQ0 and DQ2 in Grouping-1) is accessed simultaneously in the 4-bit area of different column addresses, some data is transferred to the input / output terminal DQ. For, it is necessary to replace the terminals, that is, to use another DQ data bus.

  FIG. 15 is a diagram for explaining the special memory mapping of FIG. FIG. 15 shows an image processing system using a memory having an input / output bit width of 4 bits. In particular, an image processing system using even DQ of the memory for luminance information of each pixel and odd DQ for color difference information of each pixel. It is. FIG. 15A shows a case where only luminance information is accessed, and FIG. 15B shows a case where only color difference information is accessed.

  The pixel positions (X0 to X5) on the screen indicate the physical positions on the same screen on the left and right. Each pixel position holds “A, C, E, G, I, K” as “luminance information” and “B, D, F, H, J, L” as “color difference information”.

  Here, when the image processing system generates the rectangular access 151 for the luminance information “CEGI” at the pixel positions X1-X4, the memory accesses only the even DQ as shown in FIG. 15A (153 in the figure). When the rectangular access 152 for the color difference information “DFHJ” is generated, the memory must access only the odd DQ (154 in the figure) as shown in FIG.

  For this reason, the minimum information that the memory needs to receive is information indicating whether the system uses a method that maintains luminance information in even DQ and color difference information in odd DQ (whether access is required every 1 DQ) (BMR = AL), an address (CA) including a bit as a starting point, and position information (SB) of a bit as a starting point in the 4-bit area of the address. These column address CA and bit combination information SB and BMR have already been described with reference to FIG.

  In this case, the same DQ (for example, DQ0 or DQ2 in Grouping-1) is accessed at different addresses at the same time, so the data is transferred to the input / output terminals. It is necessary to replace the terminals to use the data bus. For this purpose, a plurality of switches indicated by white and black circles are provided in the memory, and these switches are controlled based on the information SB and MBR.

  FIG. 16 is a timing chart showing a byte boundary function in rectangular access. This rectangular access is an example of accessing the rectangular area 22 in FIG. As described above, in rectangular access, any combination of byte data (bit data) from any byte position (or bit position) in the memory unit area (4-byte area or 4-bit area) selected by the column address CA. Are read out, the first information SB and the second information BMR are required as the first column address CA and the byte combination information 166.

  FIG. 16A shows an example in which these byte combination information SB and BMR are supplied together with the read command RD. The bank address BA = 2 and the row address RA = 2 are supplied by the active command ACT (161 in the figure), and the head byte is sent together with the bank address BA = 2 and the column address CA = 0 by the subsequent read command RD (162 in the figure). First information SB = 2 ((163 in the figure) indicating the (first bit) position and second information BMR = V (165 in the figure) indicating a combination of bytes (bits) are supplied. 6, the first 4 bytes (4 bits) of the rectangular area 22 are output to the input / output terminal DQ, and the remaining three sets of 4 bytes (4 bits) of the rectangular area 22 are also the same bank address BA and column address. It is specified by CA and byte combination information SB and BMR.

  In FIG. 16B, of the byte combination information SB and BMR, the second information BMR (165 in the figure) is the mode register set command EMRS (in the figure) in the register access mode before the active command ACT is issued. 167) and the second information BMR is recorded in a mode register in the memory. In the subsequent rectangular access, column access is performed based on the second information BMR. The active command ACT (161 in the figure) and the read command RD (162 in the figure) in the rectangular access are the same as those in FIG. 16A except for the second information BMR.

  The second information BMR = V is various in big endian (V = UP), little endian (V = DOWN), when luminance information is stored in even DQ, and color difference information is stored in odd DQ (V = AL). Can have a lot of information.

  The image system can realize a byte boundary function in rectangular access by any of the systems shown in FIGS.

  FIG. 17 is a configuration diagram of an image processing system for realizing the byte boundary functions. Similarly to FIG. 8, a memory control unit 82 for controlling the image memory 86 is provided. The memory control unit 82 provides address information BA, RA, CA, and a 4-byte area (or selected by the address information). Byte combination information (bit combination information) 166 including first information SB indicating the first byte (first bit) in the 4-bit area) and second information BMR indicating a combination of bytes, and operation commands ACT, RD , EMRS are supplied to the image memory 86.

  As described above, in the timing chart (A), the byte combination information SB and BMR (166 in the figure) are supplied simultaneously with the read command RD or the write command WT (not shown). In the timing chart (B), the second information BMR is supplied simultaneously with the mode register set command EMRS (167 in the figure), and the first information SB is supplied simultaneously with the read command RD or the write command WT (not shown).

  FIG. 18 is a diagram showing a byte boundary function. This figure is the same as the rectangular access in FIG. In FIG. 10 and subsequent figures, the case where the memory unit area selected by the column address CA is a 4-bit area has been described as an example. However, as described above, when the memory unit area is a 4-byte area, rectangular access is possible by the byte boundary function. FIG. 18 shows this again.

  In the example of FIG. 18, in order to efficiently access the rectangular area 22 in the page area 14 (BA = 0, RA = 0), together with the read command RD (167 in the figure), the bank address BA, the column address CA and , Byte combination information 166 composed of the first information SB and the second information BMR is issued. In response to this, 4-byte data BY0-3 in the rectangular area 22 is simultaneously output to the input / output terminal DQ. A similar operation is performed in the case of the write command WT. That is, the four 4-byte terminals BY0-3 of the input / output terminal DQ are associated with the byte data in CA1, CA1, CA0, CA0 corresponding to the first read command RD, and the next read command RD. Corresponding to each byte data in CA5, CA5, CA4 and CA4. The correspondence between the column addresses corresponding to the remaining read commands RD and the input / output terminals is as shown in the figure.

  In this manner, the bit boundary and byte boundary functions can be realized in the same manner regardless of whether the input / output terminal DQ is 4 bits wide or 32 bits (4 bytes) wide.

  FIG. 19 is a configuration diagram of an image processing system that realizes a simplified byte boundary function. As described above, one of two types of memory mapping, big endian and little endian, can be selected in system design. Correspondingly, in the above-described embodiment, byte-shifted rectangular access is specified by specifying BMR = UP for big endian and BMR = DOWN for little endian in the second information BMR of the byte combination information. Even so, the pixel on the image can be associated with the byte position in the memory space.

  In the example of FIG. 19, when the memory mapping 12 is designed to support little endian, the image memory 86 and the memory control unit 82 can be used even if only the byte boundary function corresponding to big endian can be supported in the memory space 15. By providing the input / output terminal group switching means 190 between the two, the whole system can realize a byte boundary function corresponding to little endian.

  That is, when the memory mapping on the system side is little endian, the switching means 190 is provided to replace 0 and 3 of both input / output terminal groups from 3 to 0. As a result, since the system side can be regarded as supporting big endian when viewed from the image memory, a little endian byte boundary function can be realized even with a memory configuration corresponding only to the second information BMR = UP.

  FIG. 20 is a diagram illustrating an image processing system that implements the simplified byte boundary function of FIG. FIG. 20 (1) is an example in which the image processing system 80 and the image memory 86 are connected by the connection unit 200 that is connected without replacing the input / output terminals T0 to T3. FIG. This is an example in which the connection unit 190 is connected. In any case, the image memory 86 has only a bit boundary function corresponding to big endian, and the image processing system 80 uses the 4-bit data of the input / output bit width as the pixel position X0-X3 and the input / output terminal T3- It is a little endian type corresponding to T1.

  In FIG. 20 (1), when the address unit is accessed (A), the pixel position (X0-X7) on the screen and the address (CA) on the memory side are one-to-one (X0-X3 and CA = 0, X4-X7 and CA = 1), so there is no problem. However, when the signal SB is designated to perform bit-by-bit access (B), in a memory having only a bit boundary function (only BMR = UP) corresponding to big endian, the pixel position shift (X1-X4 ( BCDE), 200 in the figure, and the shift of the physical position of the memory cell (CBAH, 201 in the figure) do not match, and erroneous data CBAH is transferred. In this case, if there is a bit boundary function (BMR = DOWN) corresponding to little endian, BCDE on the memory cell can be output. However, providing the memory with a bit boundary function that can handle both big endian and little endian causes an increase in cost.

  Therefore, as shown in FIG. 20 (2), a connection unit 190 for connecting the input / output terminals on the system side and the memory side is provided, so that the pixels X0-X3 on the image correspond to DQ0-DQ3 also on the memory cells. By doing so, the little-endian image processing system 80 appears to be a big-endian system from the memory 86, so that the relationship between the pixel position shift 200 and the memory cell physical position shift 202 is one. Therefore, normal data BCDE can be transferred even if bit-shifted access corresponding to big endian is performed.

  As described above, by using the connection unit 190 that can be switched and connected by replacement, even a memory having only a bit boundary (or byte boundary) function supporting big endian can be used for an image processing system supporting little endian. Thus, a bit boundary (or byte boundary) function can be realized. In addition, in the case of a memory having a bit boundary (or byte boundary) function corresponding to both big endian and little endian, the memory and the system may be connected by the connection unit 200 that is not switched and connected.

  FIG. 21 is a diagram showing a concept of a memory configuration having a byte boundary function. This memory comprises a bit group with an arbitrary number (Nb) of 1 or more, and has an input / output terminal (Nb x N) of multiples (N) of 2 or more of the arbitrary number (Nb) of bits. The entire storage area (Nb × Ng) is configured by a plurality of bit groups (Ng) greater than a predetermined multiple (N), and any one of the plurality of bit groups (Ng) is synchronized with the first operation code. Address information that can be selected, and select the same number of bit groups as multiples (N) according to a predetermined rule starting from any one bit group selected by the address information. The plurality of bits (Nb x N) to which they belong simultaneously transfers the stored information through the input / output terminals (Nb x N).

  The arbitrary number of bits (Nb) is a concept including both a bit unit and a byte unit, and Nb = 8 (1 byte) according to the above-described embodiment. The multiple (N) expresses how many times the arbitrary number of bits (Nb) is accessed from one address, and Nb × N corresponds to the number of input / output terminals. According to the above embodiment, N = 4 and the number of input / output terminals for 4 bytes. That is, more precisely, the number of input / output terminals is Nb × N, and the number of input / output terminals = 32 (= 8 × 4).

  Ng of multiple (Ng) bit groups is the number of all bits or bytes in the memory (Nb bit bit groups), and is the number obtained by dividing the capacity of the entire storage area by Nb. Is equivalent. Usually, the number is much larger than a multiple (N) that is the number of bit groups input / output at a time. For example, in a 64-Mbit memory, Ng = 64M if Nb = 1 and Ng = 8M if Nb = 8. If we consider a 64Mbit memory according to previous examples, Nb = 8 and Ng = 8M. According to the examples so far, address information that can select any one bit group is information (SB) indicating an address (BA, RA, CA) and a starting bit, and the address (BA, RA , CA), the data narrowed down to 4 bytes is further limited to the starting byte by the information (SB) indicating the starting byte.

  Selecting the same number of bits as multiples (N) according to the rule means that according to the previous examples, selecting multiple bytes according to the information (BMR) on the combination of bytes accessed simultaneously with the starting byte, Since N = 4, if BMR = Up, four consecutive bytes in the Up direction are accessed simultaneously from any given byte.

  This is a combination of information (BA, RA, CA) that can select any one bit group (1 byte according to the previous examples) and bytes that are accessed at the same time as the starting byte information (SB). The 4 bytes selected by the information (BMR) are accessed to the image processing system via a 32-bit (= NbxN) input / output terminal.

  The memory device shown in FIG. 21 has a memory capacity of 64 bits. Therefore, there are Ng = 8 groups of bits consisting of Nb = 8 bits. The address (BA, RA, CA) and the start byte SB are composed of a total of 3 bits, and thus one bit group is selected from the bit group of Ng = 8. Further, N = 4 bit groups that are accessed simultaneously are determined by combination information (BMR). Accordingly, in the example of FIG. 21, the second group is selected by the address (BA, RA, CA) and the start byte SB, and the four groups (2 to 5 groups) that are continuous from the second group by the combination information BMR = UP. Are simultaneously accessed from the input / output terminals.

  If the memory capacity is the same 64 bits and the address increases by 1 bit, there are Ng = 16 groups of bits in units of Nb = 4 bits, and the input / output terminals are still Nb × N = 32. Multiple N = 8, and the other seven bit groups are selected by combination information BMR.

[Memory with byte boundary functions]
Next, the configuration of an image memory having a byte boundary function will be described in detail. The byte boundary function enables access to 4-byte data across the boundary of a memory unit area (4-byte area) selectable by a column address. Therefore, a function for inputting / outputting necessary 4-byte data in the memory is added. In the following description, for the sake of simplicity, a case where only the first information SB (referred to as a start byte or start bit) is given as byte combination information will be described as an example. The second information BMR is an example of fixed UP.

[Internal column control example]
First, some specific examples of column control in the memory will be described.

  FIG. 22 is a diagram illustrating a first example of an image memory having a byte boundary function. FIG. 23 is a diagram for explaining the operation of FIG.

  In FIG. 22, the same reference number is assigned to the same component as the image memory of FIG. The address signal A is input in a multiple manner, the row address RA is latched in the row address buffer 94R, and the column address CA is latched in the column address buffer 94C. The row control unit 87 supplies the row address RA to the row decoder 223 of the selected memory bank 92. The column address CA in the column buffer 94C is also supplied to the column decoder 222 in the selected memory bank.

  The memory bank 92 is divided into four memory blocks, byte areas Byte0-3. Each byte area includes a memory cell array 224, a second amplifier 225, a pair of data latches 226, 227, and a data bus switch 228. 1 byte (8 bits) of data is input / output in one access. A total of 32 bits (4 bytes) of data are input / output to / from the input / output bus I / Obus from the four byte areas. The input / output bus I / Obus is connected to 32-bit input / output terminals DQ0-31 via a buffer. In FIG. 22, only one memory bank 92 is shown, and the remaining three memory banks are omitted.

  The column control unit 90 includes a column timing controller 220 that controls the operation timing of the column decoder 222, a data latch circuit 226, 227, and a data latch selector 221 that controls the data bus switch 228. The data latch selector 221 controls the data latch circuits 226 and 227 and the data bus switch 228 in each byte area Byte0-3 according to the column address CA and the start byte SB.

  As shown in FIG. 23, it is assumed that 4-byte data from the second byte of the column address CA0 to the first byte of the column address CA1 is accessed in the page area of the row address RA0. Therefore, the start byte SB = 1.

  The memory chip 86 in FIG. 23 shows the relationship between the memory space and the input / output terminals DQ. In FIG. 23, 4-byte data of the memory unit area selected at one time by the column address CA is indicated by Q00 to Q15. That is, the 4-byte data Q00-03 is selected by the column address CA0, and the 4-byte data Q04-07 is selected by the column address CA1.

  A timing chart is shown on the right side of FIG. First, along with the active command ACT, a row address RA0 is given together with a bank address (not shown), the word line in the corresponding bank is driven, and the sense amplifier is activated. Thereafter, the column address CA0 and the start byte signal SB = 1 are given as bank combination information together with the read command RD. In response to this, the column decoder 222 in the selected memory bank 92 time-divides the internal decode signal 222D corresponding to the column address CA0 and the code signal 222D internally corresponding to CA1 obtained by incrementing CA0 by +1. The data is output to four byte areas Byte0-3. In each byte area, two sets of 1-byte data corresponding to CA0 and CA1 are cached in the data latch circuits 226 and 227. Then, the data bus switch 228 outputs 1-byte data selected according to the combination of CA0 and SB1 in each byte area from one of the data latch circuits 226 and 227 to the input / output bus I / Obus. That is, CA0 data Q01, Q02, Q03 and CA1 data Q04 are output to the I / O bus I / Obus. During a write operation, 1-byte data is input from the input / output bus to one of the data latch circuits.

  That is, the column decoder selects a column line (bit line) for one byte in each byte area in one access. In the read operation, one byte of data is selected from the memory cell array 224 in each byte area, amplified by the second amplifier 225, and cached in the data latch circuits 226 and 227. At this time, in each byte area, a memory cell mapped to the same column address CA is accessed. In order to realize byte boundary access that crosses the boundary of the memory unit area (4-byte area) that can be selected by the column address, the column decoder 222 selects the column line again after the first access is completed. The address of this column line is CA1, which is one address ahead of the previous address CA0. The 1-byte data read from the memory cell array 224 is amplified by the second amplifier and cached in the data latch circuit 227 different from the first access.

  Therefore, since the data latch circuits 226 and 227 have 8 bytes of data, which is twice the 4 bytes required by the input / output terminal DQ in one access, the data bus switch 228 has data in each byte area. One half of the data is selected from the two bytes of data cached in the latch circuit and transferred to the input / output bus I / Obus. The data latch selector 221 controls the cache operation to the data latch circuits 226 and 227 in each byte area and the switch operation at the data bus switch 228 according to the column address CA0 and the start byte signal SB = 1. Thus, byte data corresponding to different column addresses CA0 and CA1 can be transferred from each byte area to the input / output bus I / Obus.

  As a result, as shown in FIG. 23, 4-byte data Q04, Q01, Q02, and Q03 are transferred to the input / output terminal DQ via the input / output bus I / Obus. As described above, the input / output unit 93 is configured by the second amplifier 225, the data latch circuits 226 and 227, and the data bus switch 228.

  FIG. 24 is a diagram illustrating a second example of an image memory having a byte boundary function. FIG. 25 is a diagram for explaining the operation of FIG.

  In FIG. 24, the configuration different from that in FIG. 22 is that the memory cell array is divided into two arrays 224-0 and 224-1 in each byte area Byte0-3 in the memory bank 92. Circuits 226 and 227 are provided. In the pair of memory cell arrays 224-0 and 224-1, the column address CA corresponds to an even number (CA [0] = 0) and an odd number (CA [0] = 1). The column decoder 222 does not output the decode signals of CA0 and CA1 from the given column address CA0 in a time-division manner, but a pair of memory cell arrays 224 in which the two decode signals 222D0 and 222D1 are simultaneously divided. Output to -0, 224-1. In response to this, the pair of memory cell arrays output 1-byte data to the data latch circuits 226 and 227, respectively. As a result, each byte area simultaneously caches the supplied column address CA and 2-byte data of the column address incremented by +1. Then, the data latch selector 221 controls switching of the data bus switch 228 according to the column address CA and the start byte signal SB, and transfers necessary 1-byte data to the input / output bus. Each of the four byte areas outputs 1 byte of data, and a total of 4 bytes of data is output from the input / output terminal DQ.

  In the case of a write command, the 4-byte data supplied to the input / output terminal DQ is transferred to the two data latch circuits 226 via the data bus switch 228 whose switching is controlled according to the column address CA and the start byte signal SB. , 227 and written to the two memory cell arrays 224-0 and 224-1.

  FIG. 25 shows the operation when the start byte signal SB = 1 and the burst length BL = 4. Assuming that the column address CA0 and the start byte signal SB = 1 are supplied simultaneously with the read command RD and the burst length BL = 4 is set in the mode register, the column decoder 222 has the column address CA0 and CA1 obtained by incrementing it by +1. Are simultaneously supplied to the byte areas Byte0-3. In response to this, the pair of memory cell arrays 224-0 and 224-1 in each byte area outputs 1-byte data to the data latch circuits 226 and 227 via the second amplifier 225, respectively. As a result, 2-byte data is cached from each byte area. Then, based on the column data CA and the start byte signal SB, the data latch selector 221 controls which data latch circuit data is selected in each byte area (total of 4 bits in 4 byte areas, one bit at a time). Bit) is supplied to the data bus switch 228 to control the switch operation in the data bus switch. As a result, in the first cycle, 4-byte data Q04 and Q01-03 are transferred to the input / output bus I / Obus.

  In FIG. 25, since the burst length BL = 4, the column decoder 222 issues decode signals 222D0 and 222D1 corresponding to the column addresses CA2 and CA3 under the control of the column timing controller 220, and further outputs 8-byte data. The data latch circuits 22 and 227 are cached. Since the data latch circuits 226 and 227 need to hold 8-byte data of CA0 and CA1, each data latch circuit is configured to hold 2 bytes of data. As a result, 8-byte data Q08-Q15 are newly latched in the data latch circuit. Then, 4-byte data Q05-Q08 is transferred to the input / output bus by data bus switch 228 from 8-byte data Q00-Q15 held in the previous clock cycle and 8-byte data Q08-A15 held in the current clock cycle. . Therefore, the select signal S221 of the data latch selector 221 in this case is composed of 8 bits (2 bits in each byte area).

  In the next clock cycle, the column decoder 222 issues decode signals 222D0 and 222D1 corresponding to the column addresses CA4 and CA5, and caches 8-byte data Q16 to Q23 in the data latch circuit. Data bus switch 228 transfers 4-byte data Q09-Q12. In the next clock cycle, the data bus switch 228 transfers the 4-byte data Q13-Q16 to the input / output bus. At this time, it is not necessary to cache new 8-byte data from the memory cell array.

  The write operation is the same as described above. When the burst length BL = 4, 4 bytes of data are supplied to the input / output terminal DQ in 4 cycles and stored in the data latch circuits 226 and 227 via the data bus switch 228. The In response to the decode signals of column addresses CA0, 1, CA2, 3, CA4, and 5 from the column decoder 222, a total of 16 byte data is written into the memory cell array in three cycles.

  FIG. 26 is a diagram illustrating an operation of the modification (1) of the second example of the image memory having the byte boundary functions. In the example of FIG. 25, each byte area Byte0-3 caches 2 bytes of data in the pair of data latch circuits 226 and 227 simultaneously. On the other hand, in the modified example of FIG. 26, in the first column control after the read command RD, the column decoder 222 issues the internal decode signals 222D0 and 222D1 of the column addresses CA0 and CA1 simultaneously, and 2 bytes in each byte area. Are simultaneously cached in a pair of data latch circuits. In the subsequent cache operation, the column decoder 222 alternately issues the internal decode signal 222D0 on the even side (CA2, CA4) and the internal decode signal 222D1 on the odd side (CA3), and each byte area has 1 byte. Data is alternately cached in a pair of data latch circuits 226 and 227.

  That is, the 8-byte data Q00-Q07 is first cached, and the 4-byte data Q08-Q11, Q12-Q15, Q16-Q19 are cached in the data latch circuit from the next. Then, the data bus switch 228 sequentially transfers the 4-byte data DQ1-DQ4, Q05-Q08, Q09-Q12, Q13-Q16 to be transferred to the input / output bus. Also in this case, the select signal S221 of the data latch selector 221 is composed of 8 bits (2 bits in each byte area). As described above, in the read operation, the cache operation of the data from the memory cell array to the data latch circuit by the decode signal of the column address is performed in 4 cycles, and the data transfer operation from the data latch circuit to the input / output bus is also performed in 4 cycles. Done in

  Also in the case of the write operation, 4 bytes of data are supplied to the input / output terminal DQ in 4 cycles, and stored in the data latch circuits 226 and 227 via the data bus switch 228 in 4 cycles. Then, in response to the decode signals of column addresses CA0 / 1, CA2, CA3, and CA4 from the column decoder 222, a total of 16 byte data is written into the memory cell array in 4 cycles.

  FIG. 27 is a diagram illustrating the operation of the modification (2) of the second example of the image memory having the byte boundary functions. This example is an example applied to DDR (Double Data Rate). The DDR SDRAM inputs and outputs data from the DQ terminal at both the rising and falling edges of the clock CLK. That is, 4-byte data Q05-Q08 is input / output at the rising edge, and 4-byte data Q09-Q12 is input / output at the falling edge.

  Since the input / output rate is doubled in this way, it is necessary to double the amount of data cached in the memory. In the example of FIG. 27, 16 bytes of data Q00-Q03, Q04-Q07, Q08-Q11, Q12-Q15 are simultaneously cached in the data latch circuit in the first cache cycle after the read command RD, and 4 bytes from the 16-byte data. Byte data Q05-Q08 is transferred to the I / O bus at the rising edge of the clock, and the next 4-byte data Q09-Q12 is transferred to the I / O bus at the falling edge of the clock.

  In order to enable batch cache of 16-byte data as shown in FIG. 27, the memory is divided into four memory cell arrays in the byte area Byte0-3 in FIG. 24, and a second amplifier and a data latch circuit are respectively provided. Provided. In each byte area, the column decoder 222 supplies the internal decode signal of the column address CA0-3 corresponding to the head column address CA1 to the four memory cell arrays, and the 4-byte data is cached in the four data latch circuits. Is done. Then, 1-byte data of the data latch circuit selected by the data bus switch 228 by the data latch select signal S221 is transferred from the four data latch circuits to the input / output bus. In the figure, a core bus Corebus corresponds to an input / output bus of a memory cell array, and those data are cached in a data latch circuit.

  In the example of FIG. 27, the LSB (CA [0]) of the input column address CA is ignored, and the input column addresses CA0 and CA1 always correspond to the column addresses CA0-3. Data is accessed. In other words, the paired column address is fixed regardless of whether the input column address is odd or even.

  Further, in the next clock cycle, the column decoder 222 issues an internal decode signal of the column address CA4-7 to the four memory cell arrays, and further caches 4-byte data in the four data latch circuits. As a result, the 16-byte data Q16 to Q31 are latched by the data latch circuit, and the 4-byte data Q13 to Q16 and the 4-byte data Q17 to Q20 selected from the latches are generated at the rising and falling edges of the clock. Each is output.

  In the write operation, write data is written in the memory cell array from the input / output terminal DQ through the data latch circuit in the reverse direction.

  In the case of FIG. 27 as well, the data latch select signal S221 is a control signal of 8 bits in total for 2 bits in each byte area. Such a data latch select signal is generated by the data latch selector 220 in the column controller 90 according to the column address CA and the start byte signal SB.

  FIG. 28 is a diagram illustrating the operation of the modification (3) of the second example of the image memory having the byte boundary functions. This is also an example of an operation corresponding to DDR as in FIG. 27. The difference from FIG. 27 is that the combination of addresses accessed simultaneously is different depending on whether the input column address CA is odd or even. That is, the data corresponding to the input column address CA and the +1, +2, +3 CA are simultaneously accessed. That is, in the case of the input column address CA1, the data of CA1, CA2, CA3, CA4 are accessed. That is, the column decoder monitors the LSB (CA [0]) of the input column address CA and determines the column address to be accessed simultaneously.

  As shown in FIG. 28, for the input column address CA1, the column decoder generates an internal decode signal 222D0-3 of CA1-CA4, and 4 bytes data in each byte area, a total of 16 bytes data is a data latch circuit. Cached. In the next clock cycle, internal decode signals 222D0-3 of CA5-CA8 are generated, and 16-byte data is cached. Therefore, the cached 16-byte data is shifted by 4 bytes from FIG.

  Therefore, the read operation and the write operation of FIG. 28 can be realized with the same memory configuration as that of FIG.

  FIG. 29 is a diagram illustrating a third example of an image memory having a byte boundary function. FIG. 30 is a diagram for explaining the operation of FIG. In the third example, 4-byte data Q01-Q04 input / output by the byte boundary function is accessed by one column access to each byte area Byte0-3 and transferred to the input / output bus. That is, in order to access 4-byte data to the memory unit area of the adjacent column address as in the first and second examples described above, a larger number of 8-byte data or 16-byte data is stored in a plurality of memory units of the adjacent column address. Do not cache from the region.

  As shown in FIG. 29, the column control unit 90 includes a column address controller 290, and determines whether or not the column address CA should be shifted +1 to the column shifter circuit 291 in each byte area Byte 0-3 in the memory bank 92. The shift control signal S290 is supplied. Each byte area includes a column shifter 291, a column decoder 222 that decodes the output, a memory cell array 224 that inputs and outputs 1-byte data by an internal decode signal 222D, a second amplifier, a data latch circuit 226, a data bus And a switch circuit 228. In response to the shift control signal S290, the column shifter 291 in each byte area outputs the column address to the column decoder 222 with or without shifting the column address CA by +1. The data latch circuit 226 only needs to hold 1-byte data. Therefore, the data bus switch circuit 228 always selects 1-byte data in the data latch circuit 226 and transfers it to the input / output bus I / Obus.

  Referring to FIG. 30, the column address controller 290 generates CA1 by shifting the column address CA0 by +1 to the column shifter 291 in the byte area Byte0 in accordance with the input column address CA0 and the start byte signal SB. Control is performed so that the column shifters of other byte areas Byte1-3 do not shift by +1. As a result, in the byte area Byte0, 1-byte data Q04 is accessed based on the internal decode signal 222D corresponding to the column address CA1, and is latched by the data latch circuit 226. In the other byte areas Byte1-3, the 1-byte data Q01, Q02, Q03 are accessed based on the internal decode signal 222D corresponding to the column address CA0 and latched by the data latch circuit 226.

  As described above, in the third example of FIGS. 29 and 30, since the column address is generated in the memory in correspondence with the 4-byte data to be accessed, the column decoder side has a complicated structure. Since it is possible to eliminate the cache operation of byte data having more than 4 bytes, the configuration of the input / output unit 93 is simplified and the power consumption in the memory bank can be reduced.

  In the read operation, 1-byte data corresponding to the column address from the column decoder 222 is output to the data latch circuit 226 in each byte area, and transferred to the input / output terminal DQ via the data bus switch 228. In the write operation, 4-byte data input to the input / output terminal DQ is latched by the data latch circuit 226 via the data bus switch 228 in each byte area. Then, the latched data is written in the memory corresponding to the column address from the column decoder 222 in each byte area.

  The four byte areas in the bank shown in FIGS. 22 to 31 are four bit areas when the memory unit area selected by the column address is composed of four bits. One bit unit of data is accessed as a plurality of sets or a single set.

[Control with input / output terminals]
Next, an example of correspondence control between the input / output terminal DQ in the image memory and the bus or data latch circuit in the memory cell array will be described.

  FIG. 31 is a diagram showing a correspondence means with an input / output terminal of an image memory having a byte boundary function. FIG. 32 is a diagram illustrating the operation of FIG. In the means for correspondence with the input / output terminals, as shown in FIG. 32, the 4-byte data corresponding to the column address CA in the memory space is always the same input / output terminal group DQ [7: 0] to DQ [31:24. ], And the correspondence relationship is not dynamically changed. That is, the correspondence (assignment relationship) between the input / output terminal DQ and the bus in the memory (input / output bus of the memory cell array 224) is always fixed without being affected by the start byte signal SB. Therefore, even if the start byte signal SB is different between writing and reading, the input / output terminal DQ input during writing and the input / output terminal DQ output during reading are the same terminal.

  FIG. 31 shows a connection method with the DQ terminal in the case of performing 4-byte access across the boundary of the 4-byte area selected by the column address CA. This figure assumes a read operation (SB = 1) from Byte1 (Q01) in the 4-byte area in the column address CA0.

  When the input / output terminal DQ is not exchanged, the data stored as Byte1 data is always output to the DQ terminal corresponding to Byte1 without depending on the start byte signal SB. Therefore, the connection between the memory cell array 224 and the input / output buffer 94 I / O is always fixedly assigned. Therefore, the designation of the start byte signal SB is simply used to determine which column address CA bus of the memory cell array 224 should be connected to the input / output buffer 94 I / O.

  The example of FIG. 31 is a configuration example corresponding to the first example of FIG. 22 and the second example of FIG. 24, and each byte area Byte0-3 is a pair of areas (odd column address, CA [0] = 0 and even column address, CA [0] = 1). That is, as in FIG. 24, there are two memory cell areas with odd and even column addresses CA, which are further divided into four byte areas. The byte areas Byte0 Area to Byte3 Area include from the column decoder to the data latch circuit. In the case of a read operation, twice the data required for one access is output from the Byte Area, and half of the 4-byte data is input / output by the switch group of the data bus switch 228 (eight squares in the figure). Connected to buffer 94 I / O.

  When the input / output terminal DQ is not replaced in this way, the data Q01 output from the Byte1 Area of the memory cell is always connected to the input / output terminal DQ [15: 8] corresponding to Byte1 of the input / output buffer 94I / O. The Therefore, the control of the data bus switch 228 using the byte start signal SB is control of which data latch circuit in the area corresponding to the two column addresses CA is connected to the input / output buffer 94 I / O.

  The data bus switches 228 in the four byte areas Byte0-3 in FIG. 24 are collectively shown as the data bus switch 228 in FIG. Therefore, the data bus switch 228 in each byte area is composed of a pair of switches corresponding to the same input / output terminal DQ in FIG.

  FIG. 33 is a diagram showing a correspondence means with an input / output terminal of an image memory having a byte boundary function. FIG. 34 is a diagram illustrating the operation of FIG. In the means corresponding to the input / output terminals, as shown in FIG. 34, the 4-byte data corresponding to the column address CA in the memory space is sequentially input / output terminal group DQ [ 7: 0] to DQ [31:24], and the correspondence relationship is dynamically switched between the memory cell array 224 and the input / output terminal group DQ. That is, the correspondence relationship (allocation relationship) between the input / output terminal group DQ and the bus in the memory changes dynamically under the influence of the start byte signal SB. Therefore, if the start byte signal SB is different between writing and reading, the input / output terminal group DQ input during writing and the input / output terminal group DQ output during reading become different terminals.

  As is clear from FIG. 34, when the start byte signal SB = 1, the data Q01-Q04 in the memory are associated with the input / output terminal groups DQ [7: 0] to DQ [31:24]. That is, the correspondence between the bus or data latch circuit in the memory cell array and the input / output terminal group according to the start byte signal SB, the first byte data at the input / output terminal DQ [7: 0], and the remaining 3 byte data at Corresponding to the remaining input / output terminals DQ sequentially. For this purpose, the data bus switch 228 of FIG. 33 is provided with switches at all intersections between the input / output bus group I / Obus and the bus or data latch circuit of the memory cell array 224. The above-described dynamic association can be realized by controlling on / off of these switch groups by the data latch select signal S221 from the data latch selector 221.

  In this way, the input / output terminal DQ is switched for the bus or data latch circuit in the memory cell array in accordance with the start byte signal SB. Specifically, the byte data Q01 output from the byte area Byte1 in the memory cell array is connected to DQ [7: 0] corresponding to Byte0 of the input / output buffer 94I / O when SB = "1". , SB = "0", connected to DQ [15: 8]. The byte data Q05 in the byte area Byte1 is connected to DQ [23:16] when SB = "3", and is connected to DQ [31:24] when SB = "2". That is, the positions of the four switches in the closed state in FIG. 33 are shifted to the right according to the start byte signal SB.

  Next, the correspondence control between big endian and little endian in correspondence control with input / output terminals will be described.

  FIG. 35 is a configuration diagram (1) of an image memory having a byte boundary function and capable of corresponding to endian. In this example, as in the image memory described with reference to FIGS. 19 and 20, the configuration in the memory core 350 is compatible only with big endian (up mode). That is, in the byte boundary operation, only the function of accessing the 4-byte data in the up mode from the byte position corresponding to the start byte signal SB. Even in such a case, by controlling the switch group of the data bus switch 228, it is possible to realize correct data input / output with both a big endian compatible image system and a little endian compatible image system.

  In the figure, the mode register 96 is given second information BMR of byte combination information indicating the up mode or the down mode, and is set to one of the modes. However, the memory core 350 including the column decoder, the memory cell array, and the second amplifier shown in FIG. 29 is compatible only with the up mode control. That is, the column control circuit has only the up mode controller 351 and does not have the down mode controller.

  FIG. 35A shows the data bus switch 228 in the up mode. That is, in the up mode that is big endian, the memory core 350 is controlled to the up mode by the up mode controller 351. Therefore, the data bus switch 228 connects the 4-byte data bytes 0-3 of the data latch circuit 226 to the input / output buffer 94I / O as they are. That is, the core data buses cdb00z to cdb31z of the memory core 350 are directly connected to the I / O data buses pdb00z to pdb31z.

  On the other hand, FIG. 35B shows the data bus switch 228 when the down mode is set. In other words, in the case of the down mode which is little endian, the memory core 350 is controlled to the up mode by the up mode controller 351, but the data bus switch 228 stores the 4-byte data Byte 0, 1, 2 and 3 of the data latch circuit 226. , And correspond to the 4-byte bytes 3, 2, 1, 0 of the input / output buffer 94 I / O. In this case, the core bus cdbxxz and the I / O bus pdbxxz are switched in byte units.

  The data bus switch 228 shown in FIG. 35B is an example in which the same one as the input / output terminal group switching means 190 shown in FIGS. As described above, the configuration of the memory core can be adapted to either big endian or little endian, and the data bus switch 228 as described above is provided, and the switch is switched according to the down mode or the up mode. , Both endian can be supported.

  FIG. 36 is a configuration diagram (2) of an image memory having a byte boundary function and capable of corresponding to endian. Similar to FIG. 35, this image memory has a memory core configuration that can only handle up mode control, and the data bus switch 228 is set in accordance with the second information BMR = UP / DOWN set in the mode register 96. By switching, any mode can be supported. 35, the data exchange by the data bus switch 228 is performed so that the MSB (DQ31) and the LSB (DQ00) are exchanged. That is, in addition to the replacement of 4 bytes, the 8-bit data of each byte is also replaced.

  FIG. 37 is a configuration diagram (3) of an image memory having a byte boundary function and capable of corresponding to endian. This image memory corresponds to the image memory of FIG. 29, controls the change of the combination of column addresses in the four byte areas in the memory core 350 corresponding to the operation mode, and starts from the byte corresponding to the start byte signal SB. 4-byte data in the up direction or down direction is input / output from the four memory arrays.

  For example, as shown in FIG. 30, when the column address CA0 and the start byte SB = 1, the internal column addresses of the four byte areas Byte0-3 are CA1, CA0, CA0, CA0 in the up mode, and the data Q04, Q01, Q02, and Q03 are input / output from the 4-byte input / output terminal DQ. On the other hand, in the down mode, they are CA0, CA0, CA1, CA1, and data Q00, Q01, Q06, Q07 are input / output from the 4-byte input / output terminal DQ.

  In this way, the column shifter 291 switches column data to be given to the four byte areas Byte0-3 in the memory core between the up mode and the down mode. A combination of column addresses uniquely determined by the start byte signal SB and the mode signal BMR is supplied to each byte area in the memory core 350 via the column shifter 291. The column shifter 291 selects one of the four column addresses caby0z-caby3z from the column address control unit 90A that needs to be switched according to the up mode / down mode Up / Down. In other words, in the byte area Byte0, either caby0z or caby3z is selected, in the byte area Byte1, either caby1z or caby2z is selected, in the byte area Byte2, either caby1z or caby2z is selected, and the byte In the area Byte3, either caby0z or caby3z is selected.

  In the case of a single data rate (SDR), it is sufficient that 4-byte data can be input / output in one access. Therefore, as described with reference to FIG. 29, 1-byte data held in the data latch circuit corresponding to each byte area is used as it is. Transfer to the input / output bus.

  On the other hand, in the case of a double data rate (DDR), it is necessary to input / output 8 bytes of data 4 bytes at a time in one access. Therefore, in the configuration of FIG. 29, each byte area Byte0-3 has a block of even column address (CA [0] = 0) and a block of odd column address (CA [0] = 1). The column data of the combination uniquely determined by the start byte signal SB and the mode signal BMR is supplied from the column shifter 291 to the pair of blocks, and the necessary 4-byte data is selected by the data bus switch 228 to the input / output bus I / Obus. Forward. In this case, each switch in the data bus switch 228 selects even-numbered block or odd-numbered block data according to the control signal dabyaz-dabydz from the data latch selector 221 and transfers it to the input / output bus I / Obus. For this reason, the data latch selector 221 is supplied with the data bus column address daby0z-daby3z from the column address control unit 90B, and the data latch selector 221 has four byte areas according to the up / down mode Up / Down. Select one of the two that needs to be switched. This combination of switching candidates is the same as that of the column shifter 291 described above.

  As shown in FIG. 37, the number of switches in the switch group of the data bus switch 228 can be reduced by controlling the combination of column addresses. That is, in the data bus switch shown in FIGS. 35 and 36, if the number of input / output terminals DQ is N bytes, 2N * 8 switches are required. However, by controlling the combination of column addresses as shown in FIG. 37, 2N switches are required for the column shifter 291 and the data bus switch 228, respectively, and a total of 4N switches are required. Therefore, the number of switches can be reduced to ¼ as compared with FIGS.

  FIG. 38 is an operation timing chart of an up mode in the DDR memory of FIGS. 38 and 37. This example is an example of the column address CA1 and the start byte signal SB = 1, and is an example of reading data DQ05 to DQ08 stored in the memory 86 with big endian. That is, the relationship between the data Q00 to Q19 and the input / output terminal DQ with respect to the column address in the memory 86 is as illustrated.

  As described above, in the case of the DDR memory, each byte area in the memory cell array has an even column address block (CA [0] = 0) and an odd column address block (CA [0] = 1). The controlled combination column address caby is supplied to these blocks, and the controlled data bus switching column address daby is supplied to the data bus switch 228.

  That is, CA1 is input as the column address CA serving as the base point. Accordingly, the column address CA supplied to the even number block (CA [0] = "0") and the odd number block (CA [0] = "1") in each byte area Byte0-3 is controlled. In the block (CA [0] = "0") area, the column line of the column address CA2 is activated, and in the odd block (CA [0] = "1"), the byte area Byte 0 has the column address CA3. The column line is activated, and the column line of the column address CA1 is activated in the byte areas Byte1, 2, and 3.

  As a result, data Q05 to Q12 are output to the core bus of the memory core. That is, data Q08-Q11 is output to the even-numbered core bus, and data Q5-Q7, Q12 is output to the odd-numbered core bus.

  In DDR memory, it is necessary to transfer 4-byte data from this 8-byte data to the I / O bus. Therefore, the data bus switch selects the data of the even block (CA [0] = "0") only in the byte area Byte0 based on the start byte signal SB and the column address CA, and inputs the data Q05 to Q08 as a result. Can be output to the output terminal DQ.

  Here, in each of the even and odd areas (CA [0] = "0" / "1"), the internal column address cabyaz selects caby0z, the internal column address cabybz selects caby1z, cabycz selects caby2z, and cabydz Each caby3z is selected. Similarly, column address dabyaz for the data bus selects daby0z in each of the even and odd areas (CA [0] = "0" / "1"). Similarly, dabybz selects daby1z, dabycz selects daby2z, dabydz has selected daby3z respectively.

  FIG. 39 is an operation timing chart of the down mode in the DDR memory of FIG. This example is an example of the column address CA1 and the start byte signal SB = 2, and is an example of reading data DQ05 to DQ08 stored in the memory 86 in little endian. That is, the relationship between the data Q00 to Q19 and the input / output terminal DQ with respect to the column address in the memory 86 is as illustrated. The relationship between the 4-byte data and the input / output terminal DQ is opposite to that in FIG.

  In this case, CA1 is input as the column address CA serving as the base point. Accordingly, the column address CA supplied to the even number block (CA [0] = "0") and the odd number block (CA [0] = "1") in each byte area Byte0-3 is controlled. In the block (CA [0] = "0"), the column line of the column address CA2 is activated, and in the odd block (CA [0] = "1"), the byte area Byte 3 has the column line of the column address CA3. When activated, the column line of the column address CA1 is activated in each of the byte areas Byte2, 1,0.

  As a result, data Q05 to Q12 are output to the core bus of the memory core. That is, data Q08-Q11 is output to the even-numbered core bus, and data Q5-Q7, Q12 is output to the odd-numbered core bus.

  In DDR memory, it is necessary to transfer 4-byte data from this 8-byte data to the I / O bus. Therefore, the data bus switch selects the data Q08 of the even block (CA [0] = "0") only in the byte area Byte3 based on the start byte signal SB and the column address CA, and the rest is the data Q05 from the odd block. -07 can be selected and 4-byte data Q05 to Q08 can be output to the I / O terminal DQ.

  Here, in each of the even and odd areas (CA [0] = "0" / "1"), the internal column address cabyaz selects caby3z, the internal column address cabybz selects caby2z, cabycz selects caby1z, and cabydz Each caby0z is selected. Similarly, the column address dabyaz for the data bus selects daby3z in each of the even and odd areas (CA [0] = "0" / "1"). Similarly, dabybz selects daby2z, dabycz sets daby1z, dabydz selects daby0z.

  As described above, compared with the up mode of Fig. 38, by replacing cabyz and dabyz with byte areas Byte0 and Byte3, and further replacing byte areas Byte1 and Byte2, correspondence between two types of byte data, big endian and little endian. can do. FIG. 40 is a diagram for explaining a boundary designation method in the byte boundary function. In the figure, in the byte boundary function in which the column address CA [7: 0] is accessed beyond the boundary between the adjacent 4-byte areas of #n and # n + 1, the boundary specification method is shifted by the start byte SB. The case of value SV is considered. The start byte SB means that 4 bytes are accessed from the byte N, and the shift value SV means that 4 bytes are accessed from a position shifted N bytes from the boundary of the 4-byte area of the column address.

  In this case, the correspondence between the start byte SB and the shift value SV is different between the up mode and the down mode, corresponding to the two endian modes. In other words, in the up mode, since the byte data array is Byte0-3, SB and SV are equivalent. However, in the down mode, since the byte data array is Byte 3-0, SB and SV are not equivalent and have an inverse relationship.

  Therefore, when the image memory has only the terminal of the start byte signal SB and the internal structure is controlled according to the shift value SV, the start byte signal SB is non-inverted or inverted according to the up mode or the down mode. Thus, it is necessary to convert to shift value SV. The same applies when the image memory has only the shift value SV terminal and the internal structure is controlled according to the start byte SB.

  FIG. 41 is a diagram showing a conversion circuit between the start byte SB and the shift value SV. The conversion circuit 410 has a 2-bit configuration 410 [0], 410 [1], and includes CMOS transfer gates 412 and 413 and inverters 414 and 415, and counts indicating whether the input start byte SB is in the up mode or the down mode. Depending on the type signal, it is non-inverted or inverted and converted to a shift value SV. As shown in the truth table 411 of the conversion circuit 410, in the up mode, SB is not inverted and becomes SV, but in the down mode, SB is inverted and becomes SV.

[Column address control for rectangular access]
As shown in FIG. 1, in the memory mapping 12, 14E that associates the memory space of the image memory with the pixels of the image, in the page area 14 selected by the bank address BA and the row address RA, the matrix pixels of the image Corresponding to the arrangement, the memory unit area (4-byte area) selected by the column address CA is mapped so as to be folded with a predetermined folding width (CA Wrap). In the example of FIG. 1, the column address CA is folded back by 4 units in the page area 14. That is, the column address folding width CA Wrap is 4. This column address folding width is also referred to as a column address step.

  By mapping the memory unit area selected by the column address with a predetermined folding width, it is possible to increase the access efficiency of the rectangular access frequently performed in the image memory. In other words, while a page area is activated by an active command, a read command and a column address corresponding to the rectangular area to be accessed are repeatedly issued to access a rectangular area within the same page area. it can. Since a rectangular area within the same page area can be accessed with a single active operation, efficient access is possible.

  As shown in FIG. 16, in such rectangular access, it is necessary to repeatedly issue a read command RD, a bank address BA, a column address CA, and a start byte signal SB. However, if the mapping information of the memory, in particular, the wrapping width (CA Wrap) of the column address CA in the page area is known in advance, the image memory can be obtained by giving the first column address CA, rectangular width, and rectangular size of the rectangular area. Can access image data in a rectangular area by automatically issuing a column address to be accessed internally. In that case, the read command and the column address need only be issued once, and there is no need to issue multiple times as shown in FIG.

  FIG. 42 is a diagram for explaining automatic rectangular access using the byte boundary function. In this example, the data area accessed by the memory mapping 421 is indicated by an arrow. In this memory mapping, the column address CA is folded back to 8 within the page area. That is, the column address folding width CAWrap is 8. Therefore, the column address CA at the right end of the page area 14 has # 07, # 0F, # 17, # 1F (hexadecimal number) and the folding width CAWrap = 8. The start address of the rectangular area to be accessed is CA = # 0B, the start byte SB = 2, the width of the rectangular area Rwidth = 2 clocks (4 bytes × 2 clocks = 8 bytes), and the size of the rectangular area is the burst length. BL = 8 (4 × 8 = 32 bytes). Therefore, the height of the rectangular area is BL / Rwidth = 4.

  FIG. 43 is a timing chart for automatic rectangular access. FIG. 44 is a block diagram of an internal column address calculator required for automatic rectangular access. In order to perform the rectangular access as shown in FIG. 42, the column addresses CA = # 0B / # 0C, # 0C / # 0D, # 13 / in the memory according to the supply column addresses CA = # 0B and SB = 2. # 14, # 14 / # 15, # 1B / # 1C, # 1C / # 1D, # 23 / # 24, # 24 / # 25 should be issued. That is, in the first access, Byte 2 and 3 access CA = # 0B, and Byte 0 and 1 access CA = # 0C. In the second access, the column address CA advances by 1, and Byte2, 3 = # 0C, and Byte0,1 access CA = # 0D. In this example, since the rectangular width RWidth = 2, the next access for the third time is not the position where the column address CA has advanced by 1, but the folded column addresses CA = # 13 and # 14. Therefore, it is necessary to obtain the third column address by calculation from the column address folding width CAWrap and the rectangular width Rwidth. Considering this third address in Bytes 2 and 3, based on the current column address CA = # 0C (= 12 (decimal number)), CA Wrap = 8, RWidth = 2, the expression (CA + CAWrap−Rwidth + 1) in FIG. ), The CA for the third access is obtained as CA = 12 + 8−2 + 1 = 19 (decimal number) = # 13 (hexadecimal number). FIG. 44 shows a column address calculator in the column controller 90. This computing unit includes a column address counter 440 that increments the column address CA supplied from the outside, the column address CA (Wrap) when folded back by +1 in synchronization with the internal clock pclenz synchronized with the clock timing, and a column address counter. CA Rwap is added to the count value and the Rwidth is subtracted, the calculation unit 441, the switch 442 for selecting the output of the calculation unit 441 when the rectangular area is folded, and the synchronous clock pclenz are counted, and the horizontal count during access A rectangular width counter 444 that counts the value, and a comparator 445 that detects that the horizontal count value widthz of the rectangular width counter 444 matches the rectangular width Rwidth and generates a switching signal wrapz in the switch 442.

  This will be described with reference to the timing chart of FIG. First, it is assumed that the rectangular area size is set in the mode register as the burst length BL = 8, and the column address folding width CAWrap = 8 in the page area is also set in the mode register. Then, along with the read command following the active command, the leading column address CA = # 0B, the start byte SB = 2, and the rectangular width Rwidth = 2 to be accessed are supplied. In response to this, the timing clock pclenz is generated in synchronization with the clock, the rectangular width counter 444 counts up the horizontal count value widthz being accessed, and the column address counter 440 starts from the top column address CA = # 0B. Count up.

  The internal column address caz [7: 0] issued for the first access is CA = # 0B / # 0C as shown in FIG. In the second access, # 0C / # 0D is output corresponding to the column address caz [7: 0] = # 0C incremented by +1 by the column address counter 440. In the third access, it is necessary to return the rectangle width, the operation value of the arithmetic unit 441 is selected by the switch 442, the column address caz [7: 0] = # 03 is output, and the corresponding result after the return is obtained. Column address CA = # 13 / # 14 is generated. In the fourth, # 14 / # 15 is generated, and in the fifth, the rectangular area is folded and # 1B / # 1C is generated. After that, # 1C / # 1D, # 23 / # 24, # 24 / # 25 are generated in the same way.

  The configuration of the image memory corresponding to this automatic rectangular access is, for example, as shown in FIG. 29, and a combination of four column addresses corresponding to the byte boundary functions is supplied to the four byte areas Byte0-3. That is, the combination of the column addresses of the internal column address caz in FIG. 43 is supplied to the column decoder in each byte area. As a result, the data of these column addresses are output from the four byte areas, respectively.

  In the above example, the rectangular width Rwidth of the rectangular access is supplied together with the read command, but it may be set in the mode register in advance by the mode register set command. Alternatively, the rectangular size BL and the rectangular width Rwidth may be supplied together with the read command. The column address folding width CAWrap is set in advance by the image system, so it is desirable to set it using the mode register set command.

  In this way, when the column address CA, the rectangle width Rwidth, and the rectangle size (BL) as the starting point are given in the rectangular access, the access should be made based on the preset column address folding width CAWrap. An internal column address can be generated automatically. Therefore, rectangular access can be performed by issuing a single read command.

[Byte boundary function of page area boundary]
The byte boundary function can efficiently access data of a predetermined byte (4 bytes) across the boundary of the memory unit area (4 byte area) selected by the column address. However, when performing rectangular access beyond the page area boundary, it is necessary to activate the adjacent page area again with another active command.

  FIG. 45 is a diagram illustrating an example of a memory operation when access by the byte boundary function reaches the end of the page area. In this figure, the page area is composed of column addresses CA [7: 0] = # 00 to #FF, and the right end is an example of CA = # FF. In this case, if 4-byte data indicated by the arrow in the figure is accessed using the byte boundary function, 4-byte data can be output at SB = 0 in the up mode, but SB = 1, 2, In 3, it wraps around the right end of the page area and accesses the byte data on the left end. In other words, this is an example in which return access is performed within the same page area without performing a new active operation. In the down mode, conversely, when SB = 0, 1, 2, it is necessary to wrap from the left end to the right end (Wrap), but only SB = 3 does not require wrapping.

  When the above access is performed, only useless data is output. In order to access the next page area from the end of the page area, it is necessary to activate a neighboring page area by issuing a new active command.

  FIG. 46 is a diagram illustrating another example of the memory operation when the access by the byte boundary function reaches the end of the page area. In this example, the burst length BL is set to 8. When BL = 8 is set, the burst counter in each bank repeats counting of the internal column address with the count width of BL = 8. That is, in the example of FIG. 46, the internal column address generated by the burst counter has a width 8 of CA = # k8 to #kF (16-bit notation). Even in the case of a memory in which the access area is divided into rectangular areas based on the burst length BL by such a counter, the byte boundary function is used at the right end of the burst length area CA = # k8 to #kF as in FIG. Attempting to do so causes the same problem as in FIG. In the example of FIG. 46, folding occurs in SB = 1, 2, 3 in the up mode, and folding occurs in SB = 0, 1, 2 in the down mode. In this case, useless data is output.

  FIG. 47 is a diagram illustrating another example of the memory operation when the access by the byte boundary function reaches the end of the page area. In this example, the byte boundary operation is realized by using the multi-bank access function in the rectangular access described with reference to FIG. That is, when the row address RA = # n is specified by the active command ACT and the column address CA of the starting point is CA = # FF at the right end of the page area by the read command RD, it exceeds the boundary PB of the page area as indicated by an arrow. Access.

  That is, in the up mode, when SB = 1, 2, 3, the byte data of CA = # FF in the page area of RA = # n and the byte data of CA = # 00 in the page area of RA = # n + 1. And are accessed. In the down mode, when SB = 0, 1, and 2, the CA = # FF byte data in the RA = # n page area and the CA = # 00 byte data in the RA # n + 1 page area are accessed. Is done. In this case, since access to the adjacent page area is necessary, the page area of the row address RA = # n given together with the active command ACT is activated, and the column address CA = # FF supplied along with the read command RD In response to the start byte signal SB = 2, the page area of the adjacent row address RA = # n + 1 is activated. That is, it means that word lines in a plurality of banks are activated in response to one active command ACT.

  Thus, if control is performed so that a plurality of banks are activated in parallel, even if a byte boundary function is requested at the end of the page area, data in the necessary area can be input / output without waste.

[Other uses of byte boundary functions]
The byte boundary function enables efficient data input / output when image data is stored in a memory and data corresponding to an arbitrary pixel is accessed. The byte boundary function has the same merit in applications other than such image memory.

  48 to 50 are diagrams for explaining other uses of the byte boundary function. 48 and 49 correspond to the conventional example, and FIG. 50 corresponds to the present embodiment. As a memory configuration, a plurality of byte areas are allocated to the same column address CA, and a plurality of bytes of data allocated to the same column address CA are accessed by one access. In such a structure, access to the memory can be efficiently performed for processing of data of a fixed byte size (word configuration) allocated to the same column address CA.

  However, the size of data to be processed by the system may be less than the memory word configuration. As a coping method in such a case, there is a method of performing padding so that data of a word configuration size or less does not extend over a plurality of column address CA areas. In the example of FIG. 48, the word configuration of the memory is 4 bytes (see 483 in the figure), the data size unit to be processed is 1 byte (format A of 280 in the figure), 2 bytes (same format B), 4 bytes (same as above) Format C). For this reason, 4-byte size data can be stored so that it does not cross the column address CA by storing Byte0 as a base point. In the case of 2-byte data, it is stored at the position where Byte0 and Byte2 are the base points. 1-byte size data can be based on any position of Byte0, Byte1, Byte2, Byte3.

  Now, suppose that data 0 to 5 having a size of 2 bytes, 4 bytes, 1 byte, 2 bytes, 2 bytes, and 1 byte are continuously stored in the memory as in the write data 482 in the figure. In this case, if a write operation is performed as indicated by reference numeral 481 in the figure, padding is performed in several byte areas in the memory as indicated by reference numeral 483 in the figure, and a total of four bytes area is used for storing valid data. Not used. This means that the memory capacity is not used effectively. However, if data is output in units of 4 bytes by the column address CA, each data can be read by one column address access, so that the reading speed is increased.

  However, in order to eliminate the above-mentioned waste of storage capacity, data may be stored continuously in each byte area of the memory without padding. For example, data can be stored in a byte area in the memory as indicated by 493 in FIG. 49 by writing with a write command WR of 3 cycles as indicated by 491 in FIG.

  If data is written as shown in FIG. 49, the storage capacity of the memory can be used effectively. However, when data is stored across different column address areas, such as 2-byte data B03, B13 of data 3 or 4-byte data C01-C31 of data 1, the conventional In the memory, reading / writing cannot be executed by one column access, and two accesses are required. As indicated by reference numeral 491 in the figure, the read command RD must be issued twice for reading the data 4, and the access efficiency decreases.

  Therefore, as indicated by reference numeral 500 in FIG. 50, by using the byte boundary function, issuing a single read command RD and specifying the start byte signal SB = 3 allows different column address areas to be assigned. Data 3 (03, B13) that spans can be accessed. Therefore, a memory having a byte boundary function can improve the memory utilization rate without causing a decrease in access performance.

[Memory controller that supports byte boundary functions]
Next, a memory controller corresponding to the byte boundary function will be described. Although the image processing system has been described with reference to FIG. 8, an image processing control unit 81 and a memory control unit (memory controller) 82 are included in an image processing chip 80 in the image processing system.

  FIG. 51 is a block diagram of an image processing system. As in FIG. 8, the image processing control unit 81, the memory control unit 82, and the image memory 86 are configured. The image processing control unit 81 is configured to perform MPEG decoding processing as an example. The image processing unit 81 includes an entropy decoding processing unit 510 to which encoded and compressed stream data STM is input, an inverse quantization and inverse IDC processing unit 511 that performs data processing based on the DCT coefficient DCT-F, An intra prediction unit 512, an inter prediction unit 513 that reads a reference image to the memory control unit 82 based on the motion vector MV and the microblock division information MBdiv, and a process selection unit 515 are included. The memory control unit 82 performs memory control including issuance of commands and addresses between the image processing control unit 81 and the image memory 86. The decoded image data D-IMG output from the process selection unit 515 is stored in the image memory 86 by the memory control unit 82. In addition, the reference image read control unit 514 of the inter prediction unit 513 acquires the data of the reference image R-IMG from the image memory 86 via the memory control unit 82 and supplies the data to the process selection unit 515.

  The MPEG decoder decodes the current image data based on the reference image R-IMG in the past image or the future image read from the memory based on the motion vector and the difference data between the reference image. Accordingly, an operation of reading a rectangular reference image at the position of the motion vector from the image once stored in the image memory 86 is frequently performed. In this rectangular access control, the access efficiency can be improved by using the image memory 86 having the byte boundary function and the memory control unit 82 corresponding thereto.

  FIG. 52 is a diagram illustrating input and output signals of the memory control unit (memory controller). FIG. 53 is a diagram for explaining a reference image area to be read in a frame image. In the frame image FM-IMG, the upper left is the origin (0, 0) of the pixel coordinates, and in order to specify the area of the rectangular reference image RIMG, the upper left coordinates of the rectangle (POSX, POSY) and the vertical and horizontal sizes SIZEY and SIZEX are required. Therefore, the reference image read control unit 514 in the image processing unit supplies the above-described information (POSX, POSY), SIZEY, and SIZEEX specifying the region of the reference image RIMG to the memory controller 82. Further, a direct memory access control signal DMA-CON is input / output between the reference image read control unit 514 and the memory controller 82.

  On the other hand, the memory controller 82 calculates an address Add (bank address, row address, column address) in the memory space based on the information (POSX, POSY), SIZEY, and SIZEX specifying the reference image area, CMD, address Add, multi-bank access information SA ′, start byte signal SB, write data Data, etc. are supplied to the memory 86. In addition, read data Data read from the memory 86 is received.

  FIG. 54 is a detailed configuration diagram of the memory control unit. The memory control unit 82, from the access request source blocks 81-1 to 81-N that request access to the memory, as in the image processing control unit described above, provides information POSX, POSY, SIZEX, SIZEY of the image area to be accessed. The interface control units 541-1 to 541 -N that receive the write data Data, and the address command generation units 542-1 to 542 -N that receive the image area information and generate addresses and commands via these interface units. The interface control unit and the address command generation unit are arbitrated by the arbitration circuit 540 to determine which should be activated. The address command generation unit 542 selected and activated by the arbitration circuit 540 sends a command CMD, an address Add (bank address, row address, column address), multi-bank access information SA ′, start byte via the selector SEL. The signal SB and the like are issued to the memory 86. Thereby, the memory control unit 82 performs access control to the memory 86 and performs data writing or data reading for the access request source block selected by the arbitration. The memory control unit 82 also makes a refresh request to the memory at a necessary frequency.

  The command CMD issued by the memory control unit 82 includes commands necessary for a normal SDRAM such as a mode register set command, an active command, a read command, a write command, a precharge command, and a refresh command. In addition, the setting register 543 in the memory control unit 82 is set with the address of the upper left pixel of the frame image FM-IMG, memory mapping information, and information about the function of the memory 86. The functions possessed by the memory are, for example, a multi-bank access function and a data array switching function corresponding to endian as described later, and the presence / absence of the function possessed by the memory to be controlled is set in this setting register 543. .

  FIG. 55 is a diagram for explaining the calculation of the inter prediction unit 513 in the reference image read control unit 514. In the case of MPEG, the macro block MB is used as a processing unit. The macro block MB is composed of 16 × 16 pixel luminance data and 8 × 8 pixel color difference (Cb, Cr) data (in the case of Y: U: V = 4: 2: 0). A quarter macroblock QMB including luminance data of 8 × 8 pixels obtained by equally dividing the macroblock MB into four is a processing unit of the motion vector MV and the reference image RIMG. If the upper left coordinate of the macro block MB currently being processed is (MBaddrx, MBaddry), and the macro block division information is Mbdivx, Mbdivy, and the motion vector MV = (MVx, MVy), the arithmetic processing unit 515 is illustrated. The upper left coordinates (POSX, POSY), the horizontal width SIZEX, and the height SIZEEY of the reference image RIMG are calculated by the calculation of the arithmetic expression. This horizontal width SIZEX is set to a multiple of the number of bytes input / output in one access of the memory, and the height SIZEY is set to the number of pixels in the vertical direction.

  The reference image specifying information (POSX, POSY), SIZEY, and SIZEX calculated as described above is output from the reference image read control unit 514 to the memory controller 82, and the command address generation unit 542 in the memory controller 82 receives the above information. Based on the reference image specifying information, the memory mapping information in the setting register 543, the upper left address of the frame area, and the like, an address of the memory space necessary for rectangular access is generated.

FIG. 56 is a diagram illustrating a calculation example of the inter prediction unit 513 in the reference image read control unit 514. It is a specific example of FIG. First, the upper left coordinate of the macro block MB is (MBaddrx, MBaddry) = (0, 0), the macro block division information is Mbdivx, Mbdivy = 8, and the motion vector MV = (MVx, Mvy) = (13, 4). , The upper left coordinates (POSX, POSY), the horizontal width SIZEX and the height SIZEEY of the reference image RIMG are obtained by the following calculation.
POSX = 0 + 8 + 13 = 21
POSY = 0 + 8 + 4 = 12
SIZEX = 8, SIZEY = 8
The rectangular area of the reference image RIMG is not consistent with the unit of the 4-byte area selected by the column address. In order to match the unit of the 4-byte area, it is necessary to access an area having upper left coordinates (20, 12), a horizontal width of 12, and a height of 8, like the enlarged area E-RIMG in FIG. However, by using the byte boundary function, it becomes possible to access in units of bytes beyond the boundary of units of 4 bytes. As described above, in the access of reference image data such as MPEG, the byte boundary function contributes to improvement of access efficiency.

  FIG. 57 is a diagram illustrating an example of memory mapping. Similar to the memory mapping 12 shown in FIG. 1, the image pixels and the page area 14 in the memory space are associated like the memory mapping 12, and the adjacent page areas are arranged to have different bank addresses BA. Has been. The page area 14 is an area selected by the bank address BA and the row address RA, and each page area 14 is composed of a plurality of memory unit areas (4-byte areas) selected by the column address. In the example of FIG. 57, the page area 14 is a unit for storing image data of 64 pixels × 16 pixels.

  FIG. 58 is a diagram showing the configuration of the page area 14 in the memory mapping 12. The page area 14 specified by the row address RA0 in the bank BANK0 has memory unit areas of column addresses CA0 to CA255, 4 bytes are selected by each column address, and the folding width (step width) of the column address CA is 16. Therefore, the page area 14 has a configuration in which the width is 64 (= 4 × 16) bytes and the height is 16 (= 256/16) bytes.

  FIG. 59 is a diagram showing the arrangement of the reference image area in FIG. 56 on the memory map. As shown in FIG. 59, the reference image area RIMG has upper left coordinates (21, 12), a width of 8, and a height of 8. Therefore, the column address CA5 is set as the head address, the byte BY1 is 8 bytes, and the height is 8 bytes. Corresponds to the memory area. That is, the left end 591 of the rectangular access area is shifted by 1 byte (592 in the figure) from the boundary 590 by the column address CA. Therefore, for the memory having the above-described byte boundary function, the bank address BA0 and the row address RA0 are issued together with the active command ACT, and the head column addresses CA5, CA6 to CA117, CA118 together with the read command RD (or write command WR). And the start byte signal SB = 1 may be issued continuously. Alternatively, for the memory having the automatic internal column address generation function shown in FIGS. 42 to 44, the column address folding width CAWrap = 16 is set, and the leading column address CA5 is set together with the read command RD (or write command WR). And a start byte signal SB = 1, a rectangular width Rwidth = 2, and a burst length BL = 16.

  FIG. 60 is a diagram showing another arrangement example of the reference image area on the memory map. In this figure, the reference image area RIMG spans adjacent page areas 14-0 and 14-1. That is, it exceeds the boundary 600 of the page area. In this case, the memory having the multi-bank access function described with reference to FIG. 7 can be accessed by a single active command by issuing the multi-bank access information SA ′. If the memory does not have a multi-bank access function, it must be accessed by issuing a plurality of active commands for the banks BANK0,1. Therefore, the memory controller needs to set in the register whether or not the image memory to be controlled has a multi-bank access function, and change access control to the image memory in accordance with the setting information.

  FIG. 61 is a timing chart in the memory controller for a memory having no byte boundary function. 60 is an access example of the reference image RIMG of FIG. 59. A conventional SDRAM does not have a byte boundary function. In that case, the memory controller must perform control as shown in FIG.

  In FIG. 61, a signal 610 between the reference image read control unit and the memory controller and a signal 611 between the memory controller and the image memory are shown. As described above, the reference image read control unit 514 transmits the information on the upper left coordinates POSX, POSY, the width SIZEX, and the height SIZEEY of the reference image area together with the access request REQ to the memory controller, and the memory controller responds with the acknowledge signal. ACK is returned. It is assumed that the memory mapping information and the address of the upper left origin of the frame image are set in advance in the setting register.

  In response to this access request REQ, the memory controller issues an active command ACT, a bank address BA = 0, and a row address RA = 0 to the image memory to cause the memory to perform an active operation. Thereafter, in synchronization with the clock CLK, the memory controller issues a read command RD, a bank address BA = 0, a column address CA = 5, 6, 7 to 117, 118, 119 (24 times) to obtain 4-byte data Is received 24 times. Thereafter, the memory controller sets the strobe signal STB to H level and transmits the received data to the read control unit.

  FIG. 62 is a timing chart in the memory controller for a memory having a byte boundary function. This figure is an example of access to the reference image RIMG of FIG. 59, and is control when the memory has a byte boundary function. In the figure, a signal 620 between the reference image reading control unit and the memory controller and a signal 621 between the memory controller and the image memory are shown.

  In this case, the same signal as in FIG. 61 is transmitted from the reference image read control unit to the memory controller. The memory controller issues an active command ACT, a bank address BA = 0, and a row address RA = 0 to the image memory to cause the memory to perform an active operation. Thereafter, the memory controller performs a read command RD, a bank address Address BA = 0, column address CA = 5, 6 to 117, 118 (16 times) and start byte signal SB = 01 are issued, and 4-byte data is received 16 times. Further, the memory controller sets the strobe signal STB to the H level and transmits the received 64-byte data to the read control unit. Since the memory has a byte boundary function, the read command may be issued 16 times, resulting in high access efficiency.

  Although not shown, the column address folding width CAWrap = 16 is set for the memory having the automatic internal column address generation function shown in FIGS. 42 to 44, and the head column address CA5 is set together with the read command RD. And a start byte signal SB = 01, a rectangular width Rwidth = 2, and a burst length BL = 16. In response to this, the image memory automatically generates a column address internally and outputs the 4-byte data in the rectangular area in 16 cycles, and the memory controller continuously receives the 4-byte data 16 times.

  FIG. 63 is a timing chart of the memory controller for a memory that does not have a byte boundary function and a multi-bank access function. This example is an example of accessing the reference image RIMG of FIG. 60, and is an example of control for an image memory having no multi-bank access function. In the figure, a signal 630 between the reference image reading control unit and the memory controller and a signal 631 between the memory controller and the image memory are shown.

  As shown in FIG. 45, a memory that does not have a multi-bank access function cannot access an area that crosses a bank boundary. Therefore, in this case, the memory controller issues an active command ACT and BA = 0, RA = 0 to activate the page area 14-0, and together with the read command RD, the bank address BA = 0, column address CA = 15. ~ 127 are issued to receive 8-byte data. Further, the memory controller issues an active command ACT and BA = 1, RA = 0 to activate the page area 14-1, and together with the read command RD, the bank address BA = 1, the column address CA = 0, 1-112. , 113 is issued to receive 16-byte data. Then, the memory controller transmits the received 24-byte data to the reference image read control unit.

  FIG. 64 is a timing chart in the memory controller for a memory having a multi-bank access function and a byte boundary function. This is also an example of accessing the reference image RIMG of FIG. In the figure, a signal 640 between the reference image reading control unit and the memory controller and a signal 641 between the memory controller and the image memory are shown.

  The memory controller issues a bank address BA = 0, a row address RA = 0, and multi-bank access information SA ′ = 10 (indicating access of two banks adjacent in the horizontal direction) together with the active command ACT. In response to this, the image memory activates the bank with bank BA = 0. Then, the memory controller sequentially issues a start byte signal SB = 01, a bank address BA, and a column address CA together with the read command RD. In response to this column address CA = 15, the image memory also activates the bank with BA = 1. The memory controller receives 16 bytes of data in response to 16 read commands RD. Further, the memory controller transmits the received 16-byte data to the reference image read control unit.

  As described above, the memory controller may issue a single active command to a memory having a multi-bank access function, even if the data extends over different bank areas.

  FIG. 65 is a flowchart of the control operation of the memory controller. First, the host CPU sets ON / OFF of the multi-bank active function in the setting register in the memory controller (S1). The reference image read control unit calculates the coordinates (POSX, POSY) and size (SIZEX, SIZEY) of the reference image block from the motion vector information, macroblock division information, and target macroblock information (S2), and requests for rectangular access Are issued to the memory controller together with the rectangle parameters (S3).

  The memory controller uses the rectangular parameters (POSX, POSY) (SIZEX, SIZEY), the memory map information set in the setting register, and the address information of the frame image to issue BA, RA, CA, SB and SA ′ are calculated (S4). When the multi-bank active function is ON (YES in S5), the memory controller issues BA, RA, SA ′ together with the active command ACT, and further issues BA, CA, SB together with the read command RD, Read data is received (S6, S7, S8). In the case of a write operation, write data is output while sequentially issuing BA, CA, and SB together with a write command WR instead of a read command.

  If the multi-bank active function is OFF (NO in S5), the memory controller checks whether the requested rectangle crosses the page area, that is, the bank (S9), and if not (S9). NO) issues BA and RA together with the active command ACT, and further receives BA, CA and SB along with the read command RD while receiving read data (10, 11, 12). In the case of a write operation, write data is output while sequentially issuing BA, CA, and SB together with a write command WR instead of a read command.

  Further, when straddling banks (YES in S9), since the byte boundary function cannot be used, the memory controller calculates the coordinates POSX and the width SIZEX of the enlarged rectangular area E-RIMG shown in FIG. 56, and the corresponding upper left coordinates. Addresses BA, RA, and CA are calculated (S13). For the enlarged rectangular area, issue the BA and RA together with the active command ACT, and receive the read data while sequentially issuing BA and CA together with the read command RD (S15, 16, 17). When the reading in the upper left coordinate bank is completed (YES in S17, YES in S14), a precharge command is once generated, then an active command is generated for the next bank, and BA, Read data is received while sequentially issuing CAs (S19, S16, 17). When all the data in the bank is received (YES in S17), and when all the data is read (S18), the memory control is terminated.

  If the setting register of the memory controller is set to turn off the byte boundary function, the memory controller issues an active command, a read command, and a necessary address as shown in FIG. 61 by the configuration S13 to S18 of FIG. To do.

  In this way, the memory controller can set the byte boundary function ON / OFF and the multi-bank active function ON / OFF in the built-in setting register, and the necessary commands can be selected according to the function of the image memory to be controlled. And byte combination information such as address, multi-bank information, start byte information, up mode, down mode, and alternative are issued as appropriate.

  FIG. 66 is a flowchart of the control operation of the memory controller. In this example, it is possible to set in the memory controller whether or not the image memory to be controlled has an input / output data switching function corresponding to the endian shown in FIGS. First, the host CPU sets the presence / absence of the output data rearrangement function in the image memory in the setting register of the memory controller (S20). Then, the reference image read control unit calculates the coordinates (POSX, POSY) and size (SIZEX, SIZEY) of the reference image block from the motion vector information, macroblock division information, and target macroblock information (S21), and rectangular access. Is issued to the memory controller together with the rectangular parameters (S22).

  Next, the memory controller uses the rectangular parameters (POSX, POSY) (SIZE, SIZEY), the memory map information set in the setting register, and the address information of the frame image to issue BA, RA to be issued by rectangular access. , CA, SB, SA ′ are calculated (S23). If the output data rearrangement function is set to ON (YES in S24), the memory controller issues a bank address BA, a row address RA, and multi-bank information SA ′ together with an active command, and further a read command At the same time, a bank address BA, a column address CA, and start byte information SB are issued (S25). Thereafter, the read command, BA, CA, and SB are repeatedly issued until reading of all data is completed (S26, S27).

  On the other hand, when the output data rearrangement function is set to OFF (NO in S24), the memory controller issues a bank address BA, a row address RA, and multi-bank information SA ′ together with an active command, and further a read command At the same time, a bank address BA, a column address CA, and start byte information SB are issued (S25). Thereafter, until the reading of all data is completed, the read command, BA, CA, and SB are repeatedly issued, and rearrangement is performed so that the received data is in the order of the original image data (S28, S29, S30).

  The above FIG. 65 and FIG. 66 can be appropriately combined depending on the setting items of the setting register.

In the above embodiment, the image memory that stores digital image data in which image data of a plurality of pixels is two-dimensionally arranged has been described as an example. However, the present invention is not limited to an image memory that stores image data, and can be applied to a memory device that stores two-dimensionally arranged data other than image data based on a predetermined mapping rule. If the stored data is two-dimensionally arranged data, it may be required to access the data across a plurality of memory unit areas when accessing an arbitrary rectangular area in the two-dimensionally arranged data. In this case, the present invention can be applied.

The above embodiment is summarized as follows.

(Supplementary note 1) a memory cell array having a plurality of memory unit areas selected by an address;
Multiple input / output terminals;
An input / output unit provided between the memory cell array and a plurality of input / output terminals;
In the memory unit area, a plurality of bytes or bits of data corresponding to the plurality of input / output terminals are stored,
Further, the memory cell array and the input / output unit respond to the first operation code based on the input address and the combination information of the bytes or bits and the first memory unit area corresponding to the input address and A plurality of bytes or bits in the adjacent second memory unit area are accessed, and a plurality of bytes or a combination based on the combination information is obtained from the accessed plurality of bytes or bits in the first and second memory unit areas. A memory device, wherein a bit is associated with the plurality of input / output terminals.

(Appendix 2) In Appendix 1,
The address has a row address and a column address,
The memory cell array has a plurality of page areas selected by the row address, and the page area has a plurality of memory unit areas selected by the column address,
An active command, a read or write command is supplied, and the first operation code is the read or write command;
In response to the active command, the page area selected by the row address performs an active operation, and in response to the read or write command, the first memory unit area corresponding to the column address is adjacent to the first memory unit area. A memory device in which a plurality of bytes or bits of a combination based on the combination information are associated with the plurality of input / output terminals from a plurality of bytes or bits of a second memory unit area.

(Appendix 3) In Appendix 2,
Two-dimensional array data is stored in the plurality of memory unit areas according to a predetermined mapping rule,
The memory cell array has a plurality of banks, each bank has a plurality of page areas, each page area has a plurality of memory unit areas,
A memory device in which a bank address for selecting the bank and the row address are supplied together with the active command, and the bank address and column address and the combination information are supplied together with the read or write command.

(Appendix 4) In Appendix 3,
The combination information includes first information (SB) indicating a leading byte or a leading bit in the memory unit area, and second information (BMR) indicating the mapping rule,
A memory device in which the first information and the second information are supplied together with the read or write command.

(Appendix 5) In Appendix 3,
The combination information includes first information (SB) indicating a leading byte or a leading bit in the memory unit area, and second information (BMR) indicating the mapping rule,
The first information is supplied together with the read or write command;
The second information is supplied together with a mode register set command preceding the active command;
A memory device in which the second information is set in a mode register.

(Appendix 6) In Appendix 1,
Two-dimensional array data is stored in the plurality of memory unit areas according to a predetermined mapping rule,
The combination information includes first information (SB) indicating a leading byte or a leading bit in the memory unit area, and second information (BMR) indicating the mapping rule,
The second information indicating the mapping rule includes a big endian in which the arrangement order of the two-dimensional array data is the same as the arrangement order of the data in the memory unit area, the arrangement order of the two-dimensional array data, and the A little endian in which the order of data in the memory unit area is reversed, and an odd and even number in which the odd and even order of the two-dimensional array data is different from the odd and even order of the data in the memory unit area A memory device including any one of a mapping rule group including an inversion rule.

(Appendix 7) In Appendix 1,
The memory cell array has a plurality of banks, each bank has a plurality of page areas, each page area has a plurality of memory unit areas,
The address includes a bank address, a row address, and a column address,
The page area is selected by the bank address and the row address, the memory unit area is selected by the bank address and the column address,
An active command, a read or write command is supplied as an operation code, the first operation code is the read or write command,
A bank address and the row address for selecting the bank are supplied together with the active command, and in response thereto, a page area selected by the bank address and the row address performs an active operation,
The bank address and column address and the combination information are supplied together with the read or write command, and in response thereto, the first memory unit area corresponding to the bank address and column address and a second adjacent to the first memory unit area. A memory device in which a plurality of bytes or bits of a combination based on the combination information is associated with the plurality of input / output terminals from a plurality of bytes or bits in a memory unit area.

(Appendix 8) In Appendix 1,
The memory cell array is divided into a plurality of banks, the memory cell array in each bank has a plurality of page areas, each page area has a plurality of memory unit areas,
The address includes a bank address, a row address, and a column address,
The page area is selected by the bank address and the row address, the memory unit area is selected by the bank address and the column address,
The bank includes the memory cell array, a column decoder, a row decoder, and the input / output unit.
The input / output unit includes a data latch circuit that latches data accessed by the memory cell array, and a data bus switch circuit that selects data in the data latch circuit based on the combination information.

(Appendix 9) In Appendix 8,
In response to the read or write command, the column decoder sequentially generates a first decode signal of a supply column address and a second decode signal of a column address adjacent to the supply column address. Data corresponding to the decode signal is stored in the first data latch circuit, data corresponding to the second decode signal is stored in the second data latch circuit,
In the case of the read command, the data in the first and second data latch circuits are selected by the data bus switch circuit and output to the input / output terminal.
In the case of the write command, a memory device in which data input to the input / output terminal is stored in the first and second data latch circuits selected by the data bus switch circuit.

(Appendix 10) In Appendix 8,
In response to the read or write command, the column decoder simultaneously generates a first decode signal of a supply column address and a second decode signal of a column address adjacent to the supply column address. Data corresponding to the decode signal is stored in the first data latch circuit, data corresponding to the second decode signal is stored in the second data latch circuit,
In the case of the read command, the data in the first and second data latch circuits are selected by the data bus switch circuit and output to the input / output terminal.
In the case of the write command, a memory device in which data input to the input / output terminal is stored in the first and second data latch circuits selected by the data bus switch circuit.

(Appendix 11) In Appendix 10,
The column decoder simultaneously generates third and fourth decode signals of adjacent column addresses in addition to the first and second decode signals, and the data for the third and fourth decode signals is the first. 3, stored in the fourth data latch circuit,
In the case of the read command, the data in the first, second, third and fourth data latch circuits are selected by the data bus switch circuit and output to the input / output terminal.
In the case of the write command, a memory device in which data input to the input / output terminal is stored in the first and second data latch circuits selected by the data bus switch circuit.

(Appendix 12) In Appendix 8,
The memory cell array is divided into a plurality of bytes or bit areas, each byte or bit area having an even byte or bit area accessed by an even column address and an odd byte or bit area accessed by an odd column address. ,
The data bus switch circuit includes a switch group for connecting either an even byte or a bit area or an odd byte or a bit area to an input / output terminal group in each of the plurality of bytes or bit areas. A memory device in which a group is controlled to be conductive / non-conductive according to the supply column address and combination information.

(Appendix 13) In Appendix 8,
The memory cell array is divided into a plurality of bytes or bit areas, each byte or bit area having an even byte or bit area accessed by an even column address and an odd byte or bit area accessed by an odd column address. ,
The data bus switch circuit has a switch group for connecting either an even byte or a bit area or an odd byte or a bit area to any one of the input / output terminal groups in each of the plurality of bytes or bit areas. , A memory device in which the switch group is controlled to be conductive / non-conductive according to the supply column address and combination information.

(Appendix 14) In Appendix 13,
Two-dimensional array data is stored in the plurality of memory unit areas according to a predetermined mapping rule,
Depending on whether the combination information is an up mode or a down mode, the data bus switch circuit connects the bytes or bit data of the plurality of bytes or bit areas to the input / output terminal group in a combination of an up mode or a down mode. Memory device.

(Appendix 15) In Appendix 1,
The memory cell array is divided into a plurality of banks, the memory cell array in each bank has a plurality of page areas, each page area has a plurality of memory unit areas,
The address includes a bank address, a row address, and a column address,
The page area is selected by the bank address and the row address, the memory unit area is selected by the bank address and the column address,
The bank is divided into a plurality of bytes or bit areas, and each byte or bit area includes the memory cell array, a column decoder, and the input / output unit.
The column decoders in the plurality of byte or bit areas respectively output a column address decode signal based on the supplied column address and combination information, and the memory cell array stores byte or bit data corresponding to the decode signal. A memory device that performs input and output.

(Appendix 16) In Appendix 15,
A memory device having a column address control circuit (290) for controlling a column address to be supplied to a column decoder in the plurality of bytes or bit areas based on the supplied column address and combination information.

(Appendix 17) In Appendix 15,
The input / output unit includes a switch group that connects the plurality of byte or bit areas and the input / output terminal group, and the switch group corresponds to an up mode and a down mode of the supplied combination information. , A memory device for connecting the bytes or bit data of the plurality of bytes or bit areas to the input / output terminal group in a combination of up mode or down mode.

(Appendix 18) In Appendix 15,
Two-dimensional array data is stored in the plurality of memory unit areas according to a predetermined mapping rule,
In addition to the supplied column address and combination information, width information and rectangular size information of the rectangular area to be accessed of the two-dimensional array data are supplied,
Further, in response to a single read or write command, the plurality of byte or bit area column decoders are added to the rectangular area based on the supplied column address, combination information, rectangular area width information and rectangular size information. A memory device having a column control section for sequentially supplying corresponding column address combination groups.

(Supplementary note 19) The memory device described in supplementary note 1,
A plurality of bytes or bits in the first and second memory unit areas in the memory device by supplying the address and the combination information of the bytes or bits to the memory device together with the first operation code. And a memory system for accessing the memory system.

(Appendix 20) In Appendix 19,
In the memory device,
The memory cell array has a plurality of banks, each bank has a plurality of page areas, each page area has a plurality of memory unit areas,
The address includes a bank address, a row address, and a column address,
The page area is selected by the bank address and the row address, the memory unit area is selected by the bank address and the column address,
An active command, a read or write command is supplied as an operation code, the first operation code is the read or write command,
A bank address and the row address for selecting the bank are supplied together with the active command, and in response thereto, a page area selected by the bank address and the row address performs an active operation,
The bank address and column address and the combination information are supplied together with the read or write command, and in response thereto, the first memory unit area corresponding to the bank address and column address and a second adjacent to the first memory unit area. From a plurality of bytes or bits in the memory unit area, a plurality of bytes or bits of a combination based on the combination information are associated with the plurality of input / output terminals,
The memory controller supplies the bank address for selecting the bank and the row address together with the active command to the memory device, and supplies the bank address and column address and the combination information together with the read or write command. Memory system.

(Appendix 21) In Appendix 19,
Two-dimensional array data is stored in the plurality of memory unit areas according to a predetermined mapping rule,
The memory controller calculates the combination information of the address and the byte or bit based on information for specifying a predetermined rectangular area in the two-dimensional array data.

(Supplementary note 22) In a memory controller for controlling the memory device described in supplementary note 1,
A plurality of bytes or bits in the first and second memory unit areas in the memory device by supplying the address and the combination information of the bytes or bits to the memory device together with the first operation code. To access the memory controller.

(Appendix 23) In Appendix 22,
Two-dimensional array data is stored in the plurality of memory unit areas according to a predetermined mapping rule,
A memory controller that calculates combination information of the address and the byte or bit based on information specifying a predetermined rectangular area in the two-dimensional array data.

(Appendix 24)
In a semiconductor integrated circuit device in which circuits are integrated on a semiconductor substrate,
A memory array in which memory unit regions each having a plurality of memory cells connected to word lines and bit lines are arranged in a matrix;
An input / output unit that reads a plurality of data from a plurality of memory cells in response to a read command input from the outside;
The semiconductor integrated circuit according to claim 1, wherein the input / output unit changes a combination of the plurality of read data according to combination information.

(Appendix 25)
29. The semiconductor integrated circuit according to appendix 24, wherein the combination information is stored in a register built in the semiconductor substrate.

(Appendix 26)
27. The semiconductor integrated circuit according to appendix 25, wherein the combination information is stored in the register in response to a modeless register set command input from the outside.

(Appendix 27)
The semiconductor integrated circuit according to appendix 24, wherein the combination information is input from the outside in association with the read command.

(Appendix 28)
The semiconductor integrated circuit according to any one of appendices 24 to 27, wherein a plurality of data in the memory unit area are respectively assigned to a single column address.

(Appendix 29)
In any one of appendices 24-27, the plurality of data read in combination includes a part of the first plurality of data assigned to the first column address and a second plurality of data assigned to the second column address. A semiconductor integrated circuit composed of a part of data.

(Appendix 30)
In Appendix 29, the first plurality of data includes first, second, third, and fourth data, and the second plurality of data includes fifth, sixth, seventh, and eighth data. When the combination information is first information, the plurality of data to be read are composed of the second, third, fourth, and fifth data, and when the combination information is second information, the plurality of data to be read Data is a semiconductor integrated circuit comprising the third, fourth, fifth and sixth data.

(Appendix 31)
29. The semiconductor integrated circuit according to Supplementary Note 30, wherein when the combination information is third information, the plurality of data to be read are composed of the fourth, fifth, sixth and seventh data.

(Appendix 32)
In an image processing system having a semiconductor memory controller device and a semiconductor memory device for storing display image data,
The semiconductor memory device has a plurality of banks, each bank has a plurality of word lines, the plurality of banks are assigned different bank addresses, and the plurality of word lines in each bank are different from each other. A row address is assigned, a page area is specified by the bank address and the row address, and the page area has a plurality of memory unit areas respectively assigned to different column addresses,
The semiconductor memory controller controls to store the display image data in the plurality of page areas in the semiconductor memory device based on a predetermined memory mapping;
In this memory mapping, different bank addresses are assigned to page areas adjacent to the top, bottom, left, and right.
The image processing system, wherein the semiconductor memory device combines data in two memory unit areas based on combination information supplied from the semiconductor memory controller device and outputs the combined data to the semiconductor controller device.

(Appendix 33)
32. The image processing system according to appendix 32, wherein the combination information output from the semiconductor memory controller device is stored in a register in the semiconductor memory device.

(Appendix 34)
34. The image processing system according to claim 33, wherein the semiconductor memory controller device outputs the combination information and a modeless jitter set command, and the semiconductor memory device stores the combination information in the register in response to the modeless jitter set command.

(Appendix 35)
32. The image processing system according to appendix 32, wherein the semiconductor memory controller device outputs the combination information and a read command to the semiconductor memory device.

(Appendix 36)
In Supplementary Note 32, the page area includes a first memory unit area assigned to the first column address and a second memory unit area assigned to the second column address, from the semiconductor memory controller device. Based on the supplied combination information, the semiconductor memory device outputs data of the first and second memory unit areas to the semiconductor memory controller device.

(Appendix 37)
In Supplementary Note 36, the first memory unit area includes first, second, third, and fourth data, and the second memory unit area includes fifth, sixth, seventh, and eighth data. When the combination information is the first information, the semiconductor memory device outputs the second, third, fourth and fifth data to the semiconductor memory controller device, and the combination information is the second information. In the case of the information, the semiconductor memory device outputs the third, fourth, fifth and sixth data to the semiconductor memory controller device.

(Appendix 38)
37. The image processing system according to claim 36, wherein when the combination information is third information, the semiconductor memory device outputs the fourth, fifth, sixth, and seventh data to the semiconductor controller device.

(Appendix 39)
In the semiconductor memory controller for controlling the semiconductor integrated circuit device according to appendix 24,
A semiconductor memory controller, wherein the read command and the combination information are supplied to the semiconductor integrated circuit device.

(Appendix 40)
In semiconductor memory controller,
A command / address generator for generating a read command, a bank address, a row address, and a column address to access the semiconductor memory device;
A start byte generator for generating a start byte signal,
A page area in the semiconductor memory device is designated by the bank address and the row address, a memory unit area in the page area is designated by the column address, and a plurality of units included in the memory unit area are designated by the start byte signal. A semiconductor memory controller, wherein one data group is selected from the data groups.

(Appendix 41)
In a semiconductor integrated circuit device in which circuits are integrated on a semiconductor substrate,
An image processing control unit for decoding the encoded image data;
A memory control unit for controlling the image memory;
A setting register for setting function information indicating a function of the image memory;
The image processing unit outputs the start point coordinates of the rectangular image and the vertical and horizontal size information of the rectangular image to the memory control unit,
The memory control unit generates a command, an address, and a start byte signal for accessing the image memory based on the start point coordinates, vertical and horizontal size information, and setting information set in the setting register, and 2. A semiconductor integrated circuit device, wherein a byte signal indicates a start position of a memory unit area in an image memory selected by the address.

(Appendix 42)
Item 41. The semiconductor integrated circuit device according to item 41, wherein the setting register is further set with memory map information indicating a correspondence between the image data and the address logical space of the image memory.

(Appendix 43)
In Appendix 41, the address includes a bank address, a row address, and a column address, the page area in the image memory is specified by the bank address and the row address, and the unit memory area in the page area is specified by the column address In the semiconductor integrated circuit device, one data group in a plurality of data groups included in the unit memory area is selected by the start byte signal.

It is a figure which shows the memory mapping of the image memory in this Embodiment. It is a figure which shows two accesses in an image memory. It is a figure which shows the subject of a horizontal access. It is a figure which shows the 1st subject of a rectangular access. It is a figure which shows the 2nd subject of a rectangular access. It is a figure which shows the whole operation | movement of this Embodiment. It is a figure which shows another example of the whole operation | movement of this Embodiment. It is a block diagram of the image processing system in this Embodiment. It is a block diagram of the image memory in this Embodiment. It is a figure explaining a byte boundary function. It is a figure which shows the timing chart in a byte boundary function. It is a figure explaining the byte boundary function with respect to different mapping. It is a figure explaining the big endian and little endian of FIG. It is a figure explaining the byte boundary function in special memory mapping. It is a figure explaining the special memory mapping of FIG. It is a timing chart figure which shows the byte boundary function in rectangular access. It is a block diagram of the image processing system for implement | achieving a byte boundary function. It is a figure which shows a byte boundary function. 1 is a configuration diagram of an image processing system that realizes a simplified byte boundary function. FIG. It is a figure explaining the image processing system which implement | achieves the simplified byte boundary function of FIG. It is a figure which shows the concept of the memory structure which has a byte boundary function. It is a figure which shows the 1st example of the image memory which has a byte boundary function. It is a figure explaining the operation | movement of FIG. FIG. 24 is a diagram illustrating a second example of an image memory having a byte boundary function. It is a figure explaining the operation | movement of FIG. It is a figure which shows operation | movement of the modification (1) of the 2nd example of the image memory which has a byte boundary function. It is a figure which shows operation | movement of the modification (2) of the 2nd example of the image memory which has a byte boundary function. It is a figure which shows operation | movement of the modification (3) of the 2nd example of the image memory which has a byte boundary function. It is a figure which shows the 3rd example of the image memory which has a byte boundary function. It is a figure explaining the operation | movement of FIG. It is a figure which shows a corresponding means with the input-output terminal of the image memory which has a byte boundary function. It is a figure which shows the operation | movement of FIG. It is a figure which shows a corresponding means with the input-output terminal of the image memory which has a byte boundary function. It is a figure which shows the operation | movement of FIG. It is a block diagram (1) of the image memory which has a byte boundary function, and can respond to an endian. It is a block diagram (2) of the image memory which has a byte boundary function, and can respond to an endian. It is a block diagram (3) of the image memory which has a byte boundary function, and can respond to an endian. FIG. 38 is an operation timing chart of the up mode in the DDR memory of FIG. 37. FIG. 38 is an operation timing chart of the down mode in the DDR memory of FIG. 37. It is a figure explaining the specification method of the boundary in a byte boundary function. It is a figure which shows the conversion circuit of start byte SB and shift value SV. It is a figure explaining the automatic rectangular access using a byte boundary function. It is a timing chart figure in automatic rectangular access. It is a block diagram of an internal column address calculator required for automatic rectangular access. It is a figure which shows the example of a memory operation | movement when the access by a byte boundary function reaches the end of a page area. It is a figure which shows another example of the memory operation | movement when the access by a byte boundary function reaches the end of a page area. It is a figure which shows another example of the memory operation | movement when the access by a byte boundary function reaches the end of a page area. It is a figure explaining the other use of a byte boundary function. It is a figure explaining the other use of a byte boundary function. It is a figure explaining the other use of a byte boundary function. 1 is a configuration diagram of an image processing system. It is a figure which shows the input and output signal of a memory control part (memory controller). It is a figure explaining the reference image area | region of reading object in a frame image. It is a detailed block diagram of a memory control part. It is a figure explaining the calculation of the inter estimation part 513 in the reference image read-out control part 514. FIG. It is a figure which shows the example of a calculation of the inter estimation part 513 in the reference image read-out control part 514. It is a figure which shows the example of memory mapping. 3 is a diagram illustrating a configuration of a page area 14 in the memory mapping 12. FIG. FIG. 57 is a diagram showing an arrangement of a reference image area in FIG. 56 on a memory map. It is a figure which shows another example of arrangement | positioning on the memory map of a reference image area | region. It is a timing chart figure in a memory controller with respect to the memory which does not have a byte boundary function. It is a timing chart figure in a memory controller with respect to the memory which has a byte boundary function. FIG. 10 is a timing chart in a memory controller for a memory that does not have a byte boundary function and a multi-bank access function. FIG. 4 is a timing chart in a memory controller for a memory having a multi-bank access function and a byte boundary function. It is a flowchart figure of control operation of a memory controller. It is a flowchart figure of control operation of a memory controller.

Explanation of symbols

10: display device 12: memory mapping 14, 14E: memory unit area 15: image memory 22: rectangular area SA: refresh bank information SB, BMR: byte combination information SB: first information (start byte information) BMR: second Information (UP, DOWN, AL)
SA ': Multi-bank information

Claims (4)

In a semiconductor integrated circuit in which a circuit is integrated on a semiconductor substrate,
A memory array having a plurality of memory cells each connected to a word line and a bit line and having a plurality of memory unit areas respectively assigned to a single column address arranged in a matrix;
An input / output unit that reads a plurality of data from a plurality of memory cells in response to a read command input from the outside;
The input / output unit has a first column address and a second column address assigned to the first column address and the second column address assigned to the first column address and the second column address in the first column address and the second column address adjacent to each other. When a part of a plurality of pieces of data 2 is read in combination , the combination of the plurality of pieces of read data is changed according to combination information,
The combination information is stored in a register mounted on the semiconductor substrate.   2. The semiconductor integrated circuit according to claim 1, wherein the combination information is stored in the register in response to a modeless jitter set command input from the outside. 3. The method according to claim 2 , wherein the first plurality of data includes first, second, third, and fourth data, and the second plurality of data includes fifth, sixth, seventh, and eighth data. Thus, when the combination information is first information, the plurality of data to be read are composed of the second, third, fourth, and fifth data, and when the combination information is second information, the data is read. A plurality of data is a semiconductor integrated circuit composed of the third, fourth, fifth and sixth data. 4. The semiconductor integrated circuit according to claim 3 , wherein when the combination information is third information, the plurality of data to be read are composed of the fourth, fifth, sixth and seventh data.