As I mentioned before, I'm starting to look toward the day when this project will produce a PCB, and I've spent some time today taking a big step toward that - putting all the schematics together properly in Eagle, sorting out the IC count a bit more by using previously-unused gates where possible, and getting it to dump a prelimimary BOM.

To keep things sane, this has meant I've had to move to more than two schematic sheets. Unfortunately, that means that the schematic is no longer compatible with the free version of Eagle. While this is unfortunate, I've mitigated it somewhat by checking in (to git) the schematic as a PDF and dumping the BOM in text format. I'll keep these up to date whenever I change the source schematic, so anyone wanting to use the schematic can still access it without having to have a paid copy of Eagle.

I will admit to agonising a bit over this decision, and considered switching to a different CAD package (e.g. KiCad) but the reality is I don't know them, and I do know Eagle pretty well, so switching at this point wasn't really viable.

As always the designs are on Github. The PDF schematic can be found here, and the BOM is here. The old (obsolete) schematics are still available here.

This is a major step toward getting a PCB designed and fabbed (there's been talk of that being an Anglo-Aussie collaboration which would be awesome) and I'm pretty pleased with the results.

(In other news, I've not given up on the serial input issue I talked about in my last log. I've hacked on it a little more and gotten to the point where I need to rule out a problem with the MC68901 itself, so I've ordered five more which should be here in a week or two).