PC1-XT - ISA/XT adapter for the Commodore PC-1

The PC-1 was a very small PC clones made by Commodore, and hence it had no internal ISA/XT ports (PC expansion ports) in case you wanted to add a sound card or the like to your computer. It did, however, have an external card edge connector at the back of the chassis, for which the pin-out was somewhat similar to the internal 8-bit expansion ports used by IBM on their machines at the time (later known as ISA ports), but there were still some differences.

The PC1-XT is an adapter which lets you connect one 8-bit XT/ISA expansion card on the back of the PC-1. In theory, most XT/ISA cards should work, as long as they are 8-bit (so not the longer 16-bit ISA connectors), and they don't use other voltages than +5V and/or +12V. In fact, the PC-1's expansion port does not feature any voltage pins at all, but the PC1-XT adapter lets you "steal" some positive 5 and 12 volts supply from the computer's PSU, however the negative voltages (-5V, -12V) normally supplied by an XT/ISA connector is not provided by the PC-1's power supply, and hence not by the PC1-XT.

Confirmed to work with the PC1-XT is the XT-IDE expansion card from The Glitch Works which makes it possible to attach an IDE harddrive to an ISA/XT expansion port. In fact, extending that setup with a CF-IDE converter makes it possible to use a Compact Flash memory card as a harddrive on the PC-1.

This project on GitLab, including assembly instructions.

This project was heavily inspired by MIGs Yesterchips, episode #056 (link in German). Used with permission.