Author Topic: Hand Wired, Arduino coded Televideo 925 keyboard  (Read 2584 times)

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Offline OldIsNew

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Hand Wired, Arduino coded Televideo 925 keyboard
« on: Sat, 24 June 2017, 13:50:56 »
I've been wanting to try hand wiring  and writing firmware for a keyboard,  and after trying out mepler's TI-99 keyboard conversion tutorial
(http://www.instructables.com/id/RaspTI-Convert-a-Vintage-Computer-TI-994A-into), I set about attempting
to hand wire a Televideo 925 keyboard and then modify/write the Arduino firmware code for it. The Futuba switches on this board looked good for this kind of
project and I saw that others have done it before with success . I used the Teensy++2.0 since it has plenty of pins and I just found its size a little
easier to work with for this project than the Teensy2.0.

171478-0   171480-1




First desoldered the PCB, then wired the rows and columns:

171482-2   171484-3



171486-4   171488-5





Next decided which pins to use and then using mepler's code as a template, made the code modifications and additions for my keyboard matrix. A bit tedious coding for each key
but I really just wanted the experience of doing it. One code modification I made was to use an Active Low configuration using the Teensy internal pull-up resistors,
rather than the Active High with external pull-down resistors configuration  mepler used in his TI-99 code.


Next the very messy looking initial breadboard, uploaded my hex file to the Teensy, did a little debugging, and it worked! Once I was sure everything was working I soldered
directly to the Teensy and tucked everything back in the case. I'm sure my code is not the most elegant solution but I do feel like I learned quite a
bit by doing it (again much thanks and credit to mepler for his TI-99 matrix template and tutorial).


171490-6    171492-7


« Last Edit: Sat, 24 June 2017, 14:19:23 by OldIsNew »

Offline rowdy

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Re: Hand Wired, Arduino coded Televideo 925 keyboard
« Reply #1 on: Sun, 25 June 2017, 22:23:09 »
Fantastic restoration!

It's a testament to the construction of keyboards of old that they can (fairly) readily be repurposed for today's computers.
"Because keyboards are accessories to PC makers, they focus on minimizing the manufacturing costs. But that’s incorrect. It’s in HHKB’s slogan, but when America’s cowboys were in the middle of a trip and their horse died, they would leave the horse there. But even if they were in the middle of a desert, they would take their saddle with them. The horse was a consumable good, but the saddle was an interface that their bodies had gotten used to. In the same vein, PCs are consumable goods, while keyboards are important interfaces." - Eiiti Wada

NEC APC-H4100E | Ducky DK9008 Shine MX blue LED red | Ducky DK9008 Shine MX blue LED green | Link 900243-08 | CM QFR MX black | KeyCool 87 white MX reds | HHKB 2 Pro | Model M 02-Mar-1993 | Model M 29-Nov-1995 | CM Trigger (broken) | CM QFS MX green | Ducky DK9087 Shine 3 TKL Yellow Edition MX black | Lexmark SSK 21-Apr-1994 | IBM SSK 13-Oct-1987 | CODE TKL MX clear | Model M 122 01-Jun-1988

Ị̸͚̯̲́ͤ̃͑̇̑ͯ̊̂͟ͅs̞͚̩͉̝̪̲͗͊ͪ̽̚̚ ̭̦͖͕̑́͌ͬͩ͟t̷̻͔̙̑͟h̹̠̼͋ͤ͋i̤̜̣̦̱̫͈͔̞ͭ͑ͥ̌̔s̬͔͎̍̈ͥͫ̐̾ͣ̔̇͘ͅ ̩̘̼͆̐̕e̞̰͓̲̺̎͐̏ͬ̓̅̾͠͝ͅv̶̰͕̱̞̥̍ͣ̄̕e͕͙͖̬̜͓͎̤̊ͭ͐͝ṇ̰͎̱̤̟̭ͫ͌̌͢͠ͅ ̳̥̦ͮ̐ͤ̎̊ͣ͡͡n̤̜̙̺̪̒͜e̶̻̦̿ͮ̂̀c̝̘̝͖̠̖͐ͨͪ̈̐͌ͩ̀e̷̥͇̋ͦs̢̡̤ͤͤͯ͜s͈̠̉̑͘a̱͕̗͖̳̥̺ͬͦͧ͆̌̑͡r̶̟̖̈͘ỷ̮̦̩͙͔ͫ̾ͬ̔ͬͮ̌?̵̘͇͔͙ͥͪ͞ͅ

Offline OldIsNew

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Re: Hand Wired, Arduino coded Televideo 925 keyboard
« Reply #2 on: Mon, 26 June 2017, 22:37:30 »
Thanks rowdy! The case also included a built in speaker that I'm guessing was used for keyboard clicks and/or system sounds so I went ahead and added a piezo speaker to an empty Teensy pin and a simple one line subroutine to provide keystroke clicks. I think it actually sounds pretty good!



171686-0     171688-1

Offline rowdy

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Re: Hand Wired, Arduino coded Televideo 925 keyboard
« Reply #3 on: Tue, 27 June 2017, 21:56:48 »
Thanks rowdy! The case also included a built in speaker that I'm guessing was used for keyboard clicks and/or system sounds so I went ahead and added a piezo speaker to an empty Teensy pin and a simple one line subroutine to provide keystroke clicks. I think it actually sounds pretty good!



(Attachment Link)       (Attachment Link)

That's a nice touch to round it off - kinda period too :)
"Because keyboards are accessories to PC makers, they focus on minimizing the manufacturing costs. But that’s incorrect. It’s in HHKB’s slogan, but when America’s cowboys were in the middle of a trip and their horse died, they would leave the horse there. But even if they were in the middle of a desert, they would take their saddle with them. The horse was a consumable good, but the saddle was an interface that their bodies had gotten used to. In the same vein, PCs are consumable goods, while keyboards are important interfaces." - Eiiti Wada

NEC APC-H4100E | Ducky DK9008 Shine MX blue LED red | Ducky DK9008 Shine MX blue LED green | Link 900243-08 | CM QFR MX black | KeyCool 87 white MX reds | HHKB 2 Pro | Model M 02-Mar-1993 | Model M 29-Nov-1995 | CM Trigger (broken) | CM QFS MX green | Ducky DK9087 Shine 3 TKL Yellow Edition MX black | Lexmark SSK 21-Apr-1994 | IBM SSK 13-Oct-1987 | CODE TKL MX clear | Model M 122 01-Jun-1988

Ị̸͚̯̲́ͤ̃͑̇̑ͯ̊̂͟ͅs̞͚̩͉̝̪̲͗͊ͪ̽̚̚ ̭̦͖͕̑́͌ͬͩ͟t̷̻͔̙̑͟h̹̠̼͋ͤ͋i̤̜̣̦̱̫͈͔̞ͭ͑ͥ̌̔s̬͔͎̍̈ͥͫ̐̾ͣ̔̇͘ͅ ̩̘̼͆̐̕e̞̰͓̲̺̎͐̏ͬ̓̅̾͠͝ͅv̶̰͕̱̞̥̍ͣ̄̕e͕͙͖̬̜͓͎̤̊ͭ͐͝ṇ̰͎̱̤̟̭ͫ͌̌͢͠ͅ ̳̥̦ͮ̐ͤ̎̊ͣ͡͡n̤̜̙̺̪̒͜e̶̻̦̿ͮ̂̀c̝̘̝͖̠̖͐ͨͪ̈̐͌ͩ̀e̷̥͇̋ͦs̢̡̤ͤͤͯ͜s͈̠̉̑͘a̱͕̗͖̳̥̺ͬͦͧ͆̌̑͡r̶̟̖̈͘ỷ̮̦̩͙͔ͫ̾ͬ̔ͬͮ̌?̵̘͇͔͙ͥͪ͞ͅ