M200 interfacing continues...

From: Sellam Ismail <foo_at_siconic.com>
Date: Thu Jan 2 13:40:01 2003

On Thu, 2 Jan 2003, John Lawson wrote:

> On Thu, 2 Jan 2003, Vintage Computer Festival wrote:
> > I've got the PICK CHECK signal from the reader going into CB2. I have a
> > 1K resistor going from CB2 to ground.
> ^^^^^^^^^^^
> Try changing to 5K or even 10K (what I always use for pull ups/downs in
> TTL work. I think you're burying the poor PICK CHECK signal. Actually
> all the resistors oughta be 10K, IMHO.

I'll certainly try that. But I'm wondering why that should be necessary
when the 6522 data sheet says that particular pin is a TTL level output.

Sellam Ismail Vintage Computer Festival
International Man of Intrigue and Danger http://www.vintage.org

 * Old computing resources for business and academia at www.VintageTech.com *
Received on Thu Jan 02 2003 - 13:40:01 GMT

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