GB1058920A - Digital electric data processing apparatus - Google Patents

Abstract

1,058,920. Data processing machines. NATIONAL CASH REGISTER CO. Sept. 17, 1965 [Oct. 13, 1964], No. 39771/65. Heading G4A. A digital electric data processing machine for use as a branch sub-system in an on-line data processing system comprises a plurality of keyboard operated input-output machines 109 (Fig. 1, not shown) connected to a central data processor 101, the keys being set manually or by signals supplied by the central processor, and a series of counters, a scan counter to determine which of the input output devices communicates with the central processor during an input operation, an input row counter to control sequential read-out of data entered into rows of the keyboard, an input program counter for controlling operation of the scan and row counters and corresponding counters for output operations. As described the machine is particularly useful for operation in banks where the input output machines, known as window machines, are consulted by persons banking or withdrawing money. In operation data is entered into a window machine by its operator. The scan counter 216 reaches the count identifying this particular machine and looks causing an Answer Ready signal to be generated. Program counter 220 then advances to state 2 wherein processor 101 sends a start input signal. When counter 216 was stopped a Request to input control character was loaded in parallel into an eight flip-flop parallel to serial converter 206 which was considered empty when the first flip-flop contained a flag character and the rest were empty. A six bit character was loaded adjacent the flag character and a further flag character placed in the end position. The data was then shifted until the final flag was situated in the first flip-flop. A converter 204 is used to adjust logic voltage levels in different units. The Start Input character is shifted in a similar manner and when decoded shifts counter 220 to state 3. A Request for Character is generated when flip-flops 206 are empty and input row counter 224 advances to state 1 and counter 220 to state 4 wherein data is read from the window machine, 220 remaining in state 4 until counter 224 returns to state zero. The first four bit number sets the data bit lines 294 and generates a parity bit. The bits are also fed to a four flip-flop check register 228 each flip-flop of which adds modulo 2 to produce a check digit which is the last digit to be transmitted in each segment. A four bit digit plus a parity bit plus a bit identifying the character as data plus a flag bit are fed in parallel to register 206 and shifted out in serial fashion. When 206 is empty counter 224 advances to state 2 and the procedure repeats for the next row of the window machine until seventeen rows have been transmitted. The check character with possibly a parity bit plus the other two bits is then transmitted and is the last character in that segment. When register 206 advances to state zero 220 advances to state 5. An Input O.K. command from 101 advances 220 to state 6 otherwise a fault command causes repeat of the read in. This can be repeated three times before a Send Error lamp lights on the keyboard of the window machine, the window machine is disconnected and counter 216 resumes its scanning. To return the window machine to on-line operation a VOID key must be pressed. If O.K. command returns counter 220 advances to intial condition allowing more data to be entered via the keyboard. Data input proceeds until all the information has been entered, the final entry being the account number. The central processor checks the input data, updates its records and sends data back for entry, for instance, into a pass book. Output messages are controlled in a similar manner as described above by an output program counter 248 and an output row counter 244. Keyboard.-The keyboard (Figs. 2 and 4, not shown) incorporates nine rows of digit keys (123) and four rows of control keys (122). The keys may be depressed manually or by the action of solenoids operated by the central processor. The keys move differential actuator racks whose length of travel is proportional to the value of the key depressed. The racks also rotate selector switches (130, 131) whose contacts are connected to a program board (136). To read data a voltage is supplied to the appropriate input contact (132) and passes along a line (135) to the board (136) where the appropriate four bit digit is produced.