[Coco] Trying to get a KoKo2 working

[Bruce W. Calkins]

The matrix for the CoCo 2 is the same as that for the CoCo 1.  The CoCo 3 
added support for the four more keys filling the matrix.  I have heard a 
report of a few 6821 failures through the years.  As of a few years ago, 
Jameco Electronics listed spares.
Bruce W.
=====================

----- Original Message ----- 
From: "Chris Osborn"

>I got a KoKo 2 off eBay a few days ago, and it boots up, but the keyboard 
>doesn't work at all. I've been trying to hunt down schematics but so far 
>have only found schematics for the CoCo 1 & 3, nothing for the 2.
>
> I pulled out the logic probe to test the 6821, and I do see signals, but 
> not like I'd expect. Pin 3 is stays high, and pin 12 is oscillating. I 
> would expect since it should be scanning the matrix that several of the 
> pins to be oscillating as it scans the matrix. Is the PIA dead, or could 
> it be something else?
>
>
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