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Re: TI99/4A KEYBOARD ADAPTATION
Posted: Tue Feb 20, 2018 2:41 am
by gammaray
P5 AND 2Y0 ARE NOT USED
This is what I came up with. Did you? Combined with the other table is fully decoded.
I have not found any logic errors on your board yet but still not done...
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Tue Feb 20, 2018 4:22 am
by gammaray
Check to see if you have 2Y1 shorted with 2Y2 at "<". Following the traces it looks like it. I cant see diagram well enough to be sure. Let me know.
UPDATE: I see the "2y2" trace cut in photo from a different angle. Still looking.
One thing one has
ve to decide first I guess is do you want all the keys to stay in position like normal typewriter layout.
The second is whether you want to use the "extended keys" available or have a ZX keyboard layout.
I chose to leave keys in place, but moving the caps is also a way.
viewtopic.php?f=7&t=2771#p29847
Charles
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Tue Feb 20, 2018 5:48 pm
by gammaray
Do we need a driver board to
repeat(amplify) the signals?
https://sinclairzxworld.com/viewtopic. ... oard#p2046
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Tue Feb 20, 2018 6:58 pm
by gammaray
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Tue Feb 20, 2018 7:09 pm
by 1024MAK
Not if the wiring is kept as short as possible.
If you do want longer wiring, or want to use a multicore cable, then it's the address lines that need buffering. On the Harlequin, transistors are used.
Mark
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Tue Feb 20, 2018 7:35 pm
by gammaray
Danmoore used 12" ribbon! He is pushing the envelope. Not really, I would expect 6' to be a problem. I could test it...
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Wed Feb 21, 2018 2:13 am
by gammaray
D3 AND D4 should be crossed for Speccy operation so DPDT switch should work.
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Fri Mar 09, 2018 11:26 pm
by gammaray
- WIREDUP.png (8.38 KiB) Viewed 3939 times
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Wed Mar 14, 2018 6:00 pm
by soviet9922
Thanks for the diagrams
this last one is really help full going to give it a shot tonight.
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Wed Mar 14, 2018 6:56 pm
by gammaray
I am making a PCB to be able to connect ZX81 keyboard matrix directly into keyboard in the TI99 case and mount main board with a modified TAZ project... not there yet. Need to check pinout again before I order. TAZ 1.0 being layed out.
(Project still requires trace modification cuts to your specification, but eliminates another cable)