IMC-2001 keyboard
connector to machine (sort of a rubber version of a DB-9):
The connector on the computer side has a 9-pin DSUB connector male:
+----------- white INTR
| +--------- black GND
| | +------- green DATA
| | | +----- blue RESET
| | | | +--- Yellow CLOCK
-------------
\ O O O O O /
\ O O O O /
---------
| | | +---- red 5V
| | +------ n.c.
| +-------- n.c.
+---------- n.c.
On the keyboard PCB there is a strange white connector with the following layout:
+------------- white INTR (active low, after last clock tick)
| +----------- black GND
| | +--------- blue RESET (active low)
| | | +------- green DATA
| | | | +----- yellow CLOCK
| | | | | +--- red +5V
+-----------+
|o o o o o o|
+-----------+
| |
Keyboard layout:
Keyboard has a 8039 CPU inside and a 2K EPROM:
On the oscilloscope:
The protocol is basically ASCII over 19200 baud serial, with an interesting end signal which IMHO triggers a latch on the motherboard or so (INTR white above).
Broken keyboard cable (the black pins are just connectors added by me to test connectivity, both connector are female per default):