Exar 22-908-03 anyone ?

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Sun May 30 19:28:35 2004

>
> My Lilith workstation keyboard seems to have taken an "electric"
> beating, i.e. a 12 v to 5V short.
> The wiring inside the machine was not the best......
>
> 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.

Some later Keytronics keyboards have a 40 pin chip that contains both the
sense amplifiers and the column drivers. The number for this eludes me at
the momnet.

You might be able to get a replacement for these from another Keytronics
keyboard (e.g. a PC one).


>
> The first two are easy to replace, the Exar is much worse.
>
> Anybody have a pinout, a datasheet or an idea just what it might be ?

I should be able to find pinouts for the PERQ keyboard ICs.

Incidentally, I assume there's an EPROM in the keyboard (The 8035 has no
internal ROM, the '373 sounds like an address latch). Did this survive?
Do you have an image of it?

-tony
Received on Sun May 30 2004 - 19:28:35 BST