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?

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

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:37:14 BST