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 <[email protected]> on behalf of Chuck Guzis via cctalk <[email protected]> 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
