martinw wrote:Could I use this PCB, which I have, to make an ICE XXX?
- a XC3S500E FPGA, which is the same device as the larger GODIL
- 40 I/Os on the Hirose FX2, which is enough
- a 50MHz oscillator
- a serial port
So I think the answer is yes.
But you would definitely want to keep the cable fairly short, at least initially. I would start with 15cm.
You would have to decide on the type of level shifter technology:
- bidirectional, with pullups, e.g. using 2x 74CB3T16211 or similar
- push-pull, e.g. using 5x 74LVC4245 or similar
There are pros and cons, but it boils down to.
- Pro: level shifter board design will support different processor families (6502, Z80 and 6809), with suitable power pin strapping
- Con: the pullups cause problems in some systems (e.g. Sinclair machines with split data bus)
- Pro: should work anywhere the original processor works
- Con: level shifter board design will be specific to one processor family