31 May
2004
31 May
'04
6:47 a.m.
Tony Duell heeft op maandag, 31 mei 2004 om 02:28 (Europe/Zurich) het
volgende geschreven:
It is a 20 pin IC and it sits at the receiving end of the keyboard
matrix, the other side of the matrix is driven by two 74138.
That's it, then. An octal latching sense amplifier IIRC.
It took
out the 8035, a 74ls373 and, much worse, an unknown to me Exar
IC 22-908-03, datecode 1983
How many pins does this have?
THis sounds a lot like one of the 2 semi-custom ICs used with a
Keytronics capacitive keyboard. I've seen 22-908-3B and 22-950-3B used
in
the PERQ 2 series and elsewhere. They have 20 pins each. The former is
the (latching) sense amplifier between the 8 keyboard row lines and an
8
bit input on the microcontroller.
It seems to be the exact same IC. The keyboard is indeed a Keytronics.
You might be able to get a replacement for these from another
Keytronics
keyboard (e.g. a PC one).
I'l start looking around..
I should be able to find pinouts for the PERQ keyboard ICs.
I was hoping to kludge
a replacement with some TTL's, but this might be
difficult with a capacitive coupled keyboard.