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Re: TI99/4A KEYBOARD ADAPTATION
Posted: Thu Dec 21, 2017 8:51 am
by mooredan
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....
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Thu Feb 08, 2018 2:53 pm
by soviet9922
Have done the mod to a ti99/4 keyboard like the picture
, but i am confuse now on what pins on the keyboard should go to what rows and columns on the zx81.
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Thu Feb 08, 2018 11:33 pm
by gammaray
mooredan my know already but I see if I have time to work it out maybe not today
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Fri Feb 09, 2018 4:35 am
by soviet9922
Thanks that could be great, because i'm confused on how need to be connected to the zx81
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Fri Feb 16, 2018 12:38 am
by gammaray
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.
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.
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Sun Feb 18, 2018 7:21 pm
by gammaray
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.
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Mon Feb 19, 2018 5:35 am
by soviet9922
Thanks for the schematics i have build the keyboard modification like the pictures this is my keyboard:
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.
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Mon Feb 19, 2018 10:06 pm
by gammaray
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.
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Mon Feb 19, 2018 11:42 pm
by soviet9922
Re: TI99/4A KEYBOARD ADAPTATION
Posted: Tue Feb 20, 2018 12:47 am
by gammaray
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.