This is pretty obscure, but my dad collects Model M keyboards, and has a few of them with an AT connector. Basically its a big 5 pin connector, and although you can buy adapters from AT to PS/2, the information is transmitted differently, so to use an AT keyboard with a modern PC an active converter is required. Ive seen a website where someone built a converter using a "68HC705J1A" chip but I cannot find any for sale, looks like they were discontinued some time ago. Has anyone built or bought a converter that would work? Many thanks if you can help!