29 Apr
2020
29 Apr
'20
10:40 p.m.
Thanks in advance for any leads or on-topic discussion
of the keyboard protocol to tide me over in the meantime...
I'll see what I can find, I am sure I have some notes on it somewhere.
From what I remember, the keyboard interface is 8 bits
+ a strobe
line. Bottom 7 bits are essentially the ASCII code of the key, the MSB
is the Ctrl key (which does not affect the bottom 7 bits).
The reset button is also on the keyboard case (at the back of it) on a
PERQ 1, it just grounds a line on the connector.
There's also the DDS (diagnostic display). This is a 3 digit decimal
counter + 7 segment displays. Cleared to zero by the reset button,
incremented by a signal on the connector. The machine will run without
it, but it's very helpful to know what the microcode thinks is wrong
when the PERQ won't boot.
-tony