https://github.com/visrealm/keyboard4a99
Cherry MX compatible upgrade for your Texas Instruments TI-99/4A Mitsumi mylar keyboard
https://github.com/visrealm/keyboard4a99
cherrymx keyboard mitsumi pcb texas-instruments ti-99 ti-994a
Last synced: 5 months ago
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Cherry MX compatible upgrade for your Texas Instruments TI-99/4A Mitsumi mylar keyboard
- Host: GitHub
- URL: https://github.com/visrealm/keyboard4a99
- Owner: visrealm
- License: cern-ohl-w-2.0
- Created: 2024-03-27T04:52:31.000Z (about 2 years ago)
- Default Branch: main
- Last Pushed: 2024-04-13T05:56:25.000Z (about 2 years ago)
- Last Synced: 2024-04-14T04:08:01.087Z (about 2 years ago)
- Topics: cherrymx, keyboard, mitsumi, pcb, texas-instruments, ti-99, ti-994a
- Homepage: https://hackaday.io/project/195508-keyboard4a-99
- Size: 14.8 MB
- Stars: 4
- Watchers: 4
- Forks: 0
- Open Issues: 0
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Metadata Files:
- Readme: README.md
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README
# Introduction
Finally! a Cherry MX compatible upgrade for the infamous Mitsumi mylar keyboards that plague many unfortunate Texas Instruments TI-99/4A computers.
The upgrade consists of a new PCB and a handful of 3D printed parts. The original look is maintained by re-using the original key caps (and some other original parts). Add the switches of your choice and you're set! A brand new keyboard for your TI-99/4A.
## Only Mitsumi boards?
Currently, the upgrade is designed for the Mitsumi keyboards since their mylar innards gives the most grief to TI-99 users. It is possible other TI-99/4A keyboard brands could be adapted to use this upgrade in the future, hower that would rely on community input.
## The hardware
The Gerber file for the KEYBOARD/4A-99 PCB is available in the [/pcb](pcb) directory. I recommend the PCB is ordered in black.
#### New version: v1.1
Verion 1.1 adds support for re-using the original alpha-lock switch. The original switch provides much greater throw than the replacement I used in v1.0. As a result, the keycap adapters for v1.1 are slightly taller to match the taller alpha lock key. Also, the mounts are slightly slimmer.
STLs for all 3D printed items are located under [/stl](stl).
**Note:** Not all STLs are required.
Check out the [documentation](doc) for more details, including a [bill of materials](doc#bill-of-materials) and full build process.
## Purchasing options
KEYBOARD/4A-99 PCBs and kits are available on my Tindie store:
Also (more convenient for North America)
For those outside the US, you can support the project by purchasing direct from my [PCBWay project page](https://www.pcbway.com/project/shareproject/KEYBOARD_4A_99_0361cd65.html).
## Detailed build instructions
[](https://youtu.be/9g29EfUJuLM "KEYBOARD/4A-99 Cherry MX compatible upgrade procedure")
Also check out the [documentation](doc) for more details.
### Thanks
Thanks to [PCBWay](https://pcbway.com/g/186WQ9) for supporting this project.
[](https://pcbway.com/g/186WQ9)
### Gallery
### Licence
All hardware designs and products you can find in this repository is licensed under [CERN Open Hardware Licence Version 2 - Weakly Reciprocal](/LICENCE.txt)