TI99/4A KEYBOARD ADAPTATION

Discussions about Sinclair ZX80 and ZX81 Hardware
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mooredan
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Re: TI99/4A KEYBOARD ADAPTATION

Post by mooredan » Thu Dec 21, 2017 8:51 am

gammaray wrote:
Mon Dec 18, 2017 5:51 pm
Nice now don't forget decals for logo!

Mooredan>>
Still needs to be cleaned up a bit and I plan to cut up a junk ZX81 keyboard and glued the them onto the key caps -- but it doesn't look like the functions will fit -- may have to either exclude them or shrink them.
I cut up a laser print of keyboard with clear nail polish as adhesive and finish coat. Try on old PC key first to get the hang of it.
Thanks gammaray, I'll give that a try. My wife might have as many bottles of finger nail polish as I have capacitors -- she's got to have clear in there somewhere....
Dan Moore
Portland, Oregon, USA

soviet9922
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Re: TI99/4A KEYBOARD ADAPTATION

Post by soviet9922 » Thu Feb 08, 2018 2:53 pm

Have done the mod to a ti99/4 keyboard like the picture :D, but i am confuse now on what pins on the keyboard should go to what rows and columns on the zx81.

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gammaray
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Re: TI99/4A KEYBOARD ADAPTATION

Post by gammaray » Thu Feb 08, 2018 11:33 pm

mooredan my know already but I see if I have time to work it out maybe not today
Finish what you start. Truth is over the mountaintop or six feet under.
4 x TS1000, 2 x TS1500 , 2 x timex 2040 printer, 1/2 x timex 2020 cassette deck, ZXPAND+AY, ZeddyNET, ZXBlast..., unfinished Spectrum...Still no life!

soviet9922
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Re: TI99/4A KEYBOARD ADAPTATION

Post by soviet9922 » Fri Feb 09, 2018 4:35 am

Thanks that could be great, because i'm confused on how need to be connected to the zx81

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gammaray
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Re: TI99/4A KEYBOARD ADAPTATION

Post by gammaray » Fri Feb 16, 2018 12:38 am

This is what I worked out and 75% of 40 keys are already wired! 10 need rewiring and the rest need special circuitry and latches to utilize them for the ZX.
TIKEY IMG_20180215_173237.jpg
(3.08 MiB) Downloaded 129 times
D1-8 IS DIODE 1-8 / ASSIGNED TO A8-15 / I HAVE NOT CHECKED THE ORDER ..GOING OFF SCHEMATIC

DON'T CONFUSE WITH

K0-4 IS KBD0-4 OR ULA D0-4

I didn't mean to be.

D8 = A15
D7 = A14
D5 = A13
D3 = A12
D1 = A11
D2 = A10
D4 = A9
D6 = A8

Now maybe this makes sense. :oops:
Finish what you start. Truth is over the mountaintop or six feet under.
4 x TS1000, 2 x TS1500 , 2 x timex 2040 printer, 1/2 x timex 2020 cassette deck, ZXPAND+AY, ZeddyNET, ZXBlast..., unfinished Spectrum...Still no life!

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gammaray
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Re: TI99/4A KEYBOARD ADAPTATION

Post by gammaray » Sun Feb 18, 2018 7:21 pm

mooredan has shown the basic wiring he performed. My schematic and xref tables probably are not the same as his own implementation shown.

viewtopic.php?f=7&t=2712&hilit=mooredan#p28922

The yellow key traces have to be cut and rewired. I am working also on a revision two for expanding the key use.
Finish what you start. Truth is over the mountaintop or six feet under.
4 x TS1000, 2 x TS1500 , 2 x timex 2040 printer, 1/2 x timex 2020 cassette deck, ZXPAND+AY, ZeddyNET, ZXBlast..., unfinished Spectrum...Still no life!

soviet9922
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Re: TI99/4A KEYBOARD ADAPTATION

Post by soviet9922 » Mon Feb 19, 2018 5:35 am

Thanks for the schematics i have build the keyboard modification like the pictures this is my keyboard:
Image

looking at the schematic tried to understand how the pinout should be, i also added zxspectrum pin names because i plan to use it also on the zx spectrum the matrix is identical i guess.

this is what i understand please correct me if wrong. Because i tried several times to wire it to the computer and the keys are always on the wrong places.
Image :?:

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gammaray
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Re: TI99/4A KEYBOARD ADAPTATION

Post by gammaray » Mon Feb 19, 2018 10:06 pm

What I failed to mention is that the traces for a particular key may have to be cut so that only the new wiring is used. Now if you are having trouble then maybe your skill level is not adequate and you need further help. (I know I do!)

Please remind me which keyboard Manufacturer you have. I will take a look before proceeding.

I would recommend not cutting any traces till myself or others on the site have had a stab at determining the state of your current changes and can recommend course of action.

I will get back with you... not today but this week. After looking at your wiring changes.

Charles

PS Remember the Speccy has a change in wiring from ZX81 so you will want a DPDT (I believe) switch to reverse two lines.
Finish what you start. Truth is over the mountaintop or six feet under.
4 x TS1000, 2 x TS1500 , 2 x timex 2040 printer, 1/2 x timex 2020 cassette deck, ZXPAND+AY, ZeddyNET, ZXBlast..., unfinished Spectrum...Still no life!

soviet9922
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Re: TI99/4A KEYBOARD ADAPTATION

Post by soviet9922 » Mon Feb 19, 2018 11:42 pm

Thanks for the reply, on my previous post i attached a picture of my modified keyboard.
The matrix seem to be identical to the first post.
I have cut the traces and do the rewiring as indicated in the start of the tread, verified all cut traces and connections using my multi-meter.

Here are some pictures from my modified keyboard:
Image
Image
Image
Image
Image
Image
Image

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gammaray
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Re: TI99/4A KEYBOARD ADAPTATION

Post by gammaray » Tue Feb 20, 2018 12:47 am

Did you see mooredan's PCB mod? There are however 4 or more different manufacturers. All seem to have a slightly different traces.

Which manufacturer is yours? Not entirely necessary except some sites have good pictures.
Finish what you start. Truth is over the mountaintop or six feet under.
4 x TS1000, 2 x TS1500 , 2 x timex 2040 printer, 1/2 x timex 2020 cassette deck, ZXPAND+AY, ZeddyNET, ZXBlast..., unfinished Spectrum...Still no life!

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