Skip to content

An adapter to connect a PS/2 keyboard to a Macintosh Plus/512k/128k.

License

Notifications You must be signed in to change notification settings

lampmerchant/ps2-to-plus-keyboard

Folders and files

NameName
Last commit message
Last commit date

Latest commit

 

History

4 Commits
 
 
 
 
 
 

Repository files navigation

ps2-to-plus-keyboard

An adapter to connect a PS/2 keyboard to a Macintosh Plus/512k/128k.

Technical Details

Key Mapping

Key mapping is defined by a lookup table in the firmware and is relatively easily changed. Defaults have been chosen to be as faithful to the genuine Plus keyboard as possible.

Non-obvious mappings defined in the firmware lookup table as shipped are as follows:

PS/2 Key Plus Key User Programmable?
Alt Option No
Ctrl Command No
Super Command No
Apps Enter (key right of spacebar) No
Insert No Mapping No
Delete No Mapping No
Home No Mapping No
End No Mapping No
Page Up No Mapping No
Page Down No Mapping No
Num Lock Clear No
Print Screen Command-Shift-3 No
Scroll Lock Command-Shift-2 No
Pause Command-Shift-1 No
Escape Command-. Yes
F1 Command-Z Yes
F2 Command-X Yes
F3 Command-C Yes
F4 Command-V Yes
F5 No Mapping Yes
F6 No Mapping Yes
F7 No Mapping Yes
F8 No Mapping Yes
F9 No Mapping Yes
F10 No Mapping Yes
F11 No Mapping Yes
F12 No Mapping Yes
ACPI Power No Mapping Yes
ACPI Sleep No Mapping Yes
ACPI Wake No Mapping Yes

User Programmable Keys

Keys marked as being user programmable in the table above can have their function changed on the fly. This is done by holding down the key to be reprogrammed while typing the keystroke(s) that it should replay when pressed. Programmed key functions are stored in high-endurance flash memory and persist when power is removed.

Programmable key functions consist of a sequence of events and may consume up to 16 bytes each. Note that a key press and a key release are two separate events. Most events consume one byte each, but keypad keys (including the arrow keys) require an extra byte and may also require the firmware to modify the state of the shift key, which consumes an extra two bytes.

Pinout

Connector (from top):          PIC:
 ____                                          .--------.
||||||  1  Black   Ground              Supply -|01 \/ 08|- Ground
|1234|  2  Red     Clock        Data <--> RA5 -|02    07|- RA0 <--- PS/2 Data
|----|  3  Green   Data        Clock <--- RA4 -|03    06|- RA1 <--- PS/2 Clock
|____|  4  Yellow  +5VDC       !MCLR ---> RA3 -|04    05|- RA2 <---
 |  |                                          '--------'
 :  :

Building Firmware

Building the firmware requires Microchip MPASM, which is included with their development environment, MPLAB. Note that you must use MPLAB X version 5.35 or earlier or MPLAB 8 as later versions of MPLAB X have removed MPASM.

About

An adapter to connect a PS/2 keyboard to a Macintosh Plus/512k/128k.

Topics

Resources

License

Stars

Watchers

Forks

Releases

No releases published

Packages

No packages published