Tipro One-Handed Keyboard
Cherry MX Blue, Sublimation-Dye Keycaps, 1994
Here is something I picked up on eBay a while ago. It's a Tipro one-handed keyboard supposed to be used by people with impairments. The keyboard features a full layout, in ABCDEF arrangement, rather than QWERTY or half-QWERTY.
There are two layers of keys which can be swapped with the "Set 2" key. For easier usage with only one hand the keyboard also features a dedicated lock option for all modifier keys. This means that besides the common Caps-lock, Num-lock and Scroll-lock there is also ALT-lock, CTRL-lock and Shift-lock.
The keyboard uses the Cherry MX Blue keyswitch which seems like a pretty good choice for a one-handed keyboard. The keyboard sadly is not programmeable and only supports the default layout. The controller and key-matrix is very simple and it should not be hard to replace the controller with a different one. I currently plan to replace the controller with one from a G81-8030 and use this as an extended programmable keypad.
