What is it?

A Cherry MX compatible upgrade for the infamous Mitsumi mylar keyboards that plague many unfortunate Texas Instruments TI-99/4A computers.

The full upgrade consists of a new PCB and (optionally) a handful of 3D printed parts. The original look is maintained by re-using the original Mitsumi 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.

Note: This is an upgrade. As such, you will need an original TI-99/4A Mitsumi (or Archer) Keyboard as a donor for these parts:

• Key caps
• Alpha lock switch
• Space bar supports
• 15p Ribbon cable
• Metal support brackets

You can easily identify a Mitsumi keyboard through the bottom of your TI-99 console as it will appear brown through the vents.

3D printed parts

If you choose to print your own parts, all STLs are available in the product GitHub page. Alternatively, they can be included with your order as optional add-ons.

What do you get?

• 1x KEYBOARD/4A-99 PCB.

Add-ons

Mounting kit (optional)

• 2x Keyboard mounting brackets with brass inserts
• 2x Backing strips for Mitsumi metal support bars
• 6x Screws for mounting brackets

Key adapter kit (optional)

• 49x keycap adapters to suit Cherry MX switches and Mitsumi keycaps
• Special double-wide Shift key adapter
• 2x Spacebar support mounts with brass inserts
• 4x Screws for spacebar mounts

Akko switches (optional)

• 47x Akko Creamy Black Pro key switches

Installation video

Most orders are shipped on the next business day. Shipping times vary by location.