There are still a few problems with memory, running a memory test routine at 4MHz throws up a few spurious errors every now and again, fewer at 2MHz and non so far at 1MHz....more capacitor swapping might be in order. I'll get the soldering iron warmed up!
I've got a simple PS/2 PIC microcontroller program working - well it will display the scan code of the currently pressed key on a row of LEDs and send / receive keyboard commands. I'll hook this up to the PIO when I get it going.
First though I think I'll have a crack at getting the SIO going. I've got an SIO/2 chip here and a MAX232, should be enough to get a terminal interface going!