At 05:49 PM 5/31/00 -0400, you wrote:

I had the same problem with different keyboards as you describe.

Some keyboards require the CLOCK period to within tight margins. If I
remember
correctly this is 40us for a full period.

If the clock period is off some keyboards will not work, others will. When
I got the clock right all the keyboards worked 100%

-Jim



>You may have been following my problems getting a PIC to read the scan
>codes from an AT keyboard over the past couple of days.  Today I brought
>home a Gateway 2000 keyboard from the office and it works perfectly with my
>code.  This doesn't really solve my problem, of course, in that I still
>need to figure out why some keyboards work and some don't.  But at least I
>know that the code is doing what it's supposed to do.   For the record the
>keyboards tested are as follows:
>
>1. Cherry 84-4100.  That's the board that drops the ones.
>2. SIIG Minitouch.  The lights keep flashing when power is applied.
>3. Chicony 5161.  Old - has an XT-AT switch.  Lights come on solidly when
>power is applied.
>4. Gateway 2000 (maybe made by KTC).  Works!
>
>So what we have here is that all keyboards are not created equal!  They all
>work with my PC, but they clearly aren't all doing the same thing.  If
>anyone runs across an explanation of the differences, I'd love to hear
>it.  If I had a digital storage scope, at least I could probably figure out
>the difference between the Cherry and the Gateway since they both at least
>do something.
>
>John Hansen
>
Regards,

Jim Robertson
NEWFOUND ELECTRONICS
________________________________________
Email: newfound@pipeline.com.au
http://www.new-elect.com
MPLAB compatible PIC programmers.
________________________________________