GRI 771 Keyboard Info

[dwight]

What kind of parts does it have? If it is all ttl, you only need to connect 5 volts and ground. There will be a strobe, 7 or 8 bits of data and possible wires for repeat ( usually these go directly to the keyboards repeat switch, without logic.

Older keyboards required a negative rail. This was usually for a ROM or EPROM.

With ttl parts, finding power and ground is easy. A little checking with a scope and ascii table will quickly find the rest.

Many keyboards had stable data for both positive and negative edges of the strobe so that may not be an issue.

Dwight


________________________________
From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Chuck Guzis via cctalk <cctalk at classiccmp.org>
Sent: Monday, March 12, 2018 9:27:33 AM
To: systems_glitch via cctalk
Subject: Re: GRI 771 Keyboard Info

On 03/12/2018 07:44 AM, systems_glitch via cctalk wrote:
> All,
>
> I'm looking for info on a George Risk 771 parallel ASCII keyboard. I've got
> one but no documentation or existing cabling. I'd like to interface it to
> my Poly-88.
>
> Thanks,
> Jonathan
>


Wasn't there something about that keyboard in the Apple I documentation?
 I can't recall exactly, but it sounds familiar.


--Chuck