How many units were made, all together including Mk1, II and IIa? Are they THAT rare? I feel so lucky to have got one - it has to be the best thing I've ever bought!

4,400?

~4340-4350. There should have been 500 mk1s, but the PCB supplier screwed up. We got 400 PCBs, all allegedly bare-board tested, but at least 50 of these had internal faults which couldn't be found until populated.

Hence there were about 50 mk1s with great faults like disconnected RAS/CAS lines to the RAM, etc. Time to fault-find one of these was at least a day, so none ever got fixed/shipped. We'd have sued the PCB company for selling us known bad "tested" boards if we'd had the stomach for legal proceedings - when they were populated & found bad it was a big loss on each unit!

Hugo