Looks like they attached a drive directly to a couple of PIAs which is rough though.
Make that one PIA, one SSDA (MC6852) and a whole bunch of TTL glue attached mainly to the latter.
The glue around the SSDA is the MFM to NRZ codec.
I finished the text translation and cleanup of the prom listing scan.
The floppy code is full of delay loops, I wondered how this possibly
work with interrupts. I put up a new scan of the schematics and looking
at it this morning noticed the system doesn't have INT or NMI hooked
up at all, they just bring it out to a 25 bin expansion port.
Don't know if the p-System just makes prom calls for I/O. It's probaby easier to try HLE at the I/O adrs to try to bootstrap
it if we can extract valid sector data. I brought my machine in to the lab to see if I can get it to boot with a copy of a
floppy made with the SCP.
This system must have been a real dog to use.