Tynemouth Software Unveils Universal USB Adapter for Commodore PET Keyboards

Vintage computing specialist Tynemouth Software has announced a new universal USB adapter for all known models of the Commodore PET (Personal Electronic Transactor) keyboard — including the unusual "Separate Keyboard (SK) variant.

"There were several variations of the keyboard used on the Commodore PET, but all used the same 20 pin header with pin 2 missing as the Commodore 64 and VIC 20, although the pinout is different (and is different again from the C16 which also uses the same pin header)," writes Tynemouth Software's Dave Curran. "I originally build a USB keyboard adapter for the Commodore PET keyboards for use as a testing tool when cleaning keyboards. The early PET keyboards do occasionally get into a state where none of the keys are responding, unless maybe you press them really hard. You can start to think it is a problem with the keyboard IO chip, rather than the actual keyboard, so it is useful to be able to test the keyboard in isolation.

"I wasn't planning on selling those, but I was occasionally asked to build them, and did until I ran out of boards. I was approached by someone wanting to use one of these, but for the keyboard from an 8032-SK. This is the re-cased 80 column, 32K RAM PET (8032) in the nice rounded not-designed-by-Porsche case, and an absolutely massive separate keyboard (SK). The keyboard inside was the same as the business keyboard above, but in a detectable keyboard with a nice coiled lead and a 25 way D plug on the end. The same type of plug as used on the SX-64, C128 and CBM II, but of course with a different pinout."

With stocks of the original PET USB adapters having dwindled, and in any case being incompatible with the unusual separate keyboard, Curran revised his design to include compatibility - adding a 24-way D-socket alongside a 20-pin-header footprint suitable for the more traditional built-in keyboards. Coupled with a simple jumper — open for the "Business" model, shorted at the top for "Graphics," and shorted at the bottom for "Chiclet" - Curran's design is now universally compatible across all known PET keyboards.

The new boards — available with 25-way D-socket, 20-pin male header, or both — will be available from the Tynemouth Software Tindie store soon, with more information on their design and the differences in PET keyboards available from the Tynemouth Software blog.