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Re: S-100 Motherboard
Made some progress today but also confirmed one not easy to fix issue.
a. I patched the floppy controller (UFDC-1) to use /PRESET (75) rather
than /POC (99) to reset the board. CPU-Z and UFDC-1 now work together
like a charm all the time.
b. Started preparing the W65C02S schematics for Andrew. I hope to have
them done by Monday. When I looked closely at the board and the
existing schematics I realized that I had (mostly) documented my 2 MHz
system that used a GTE G65SC102. That device is not the same as the
W65C02S that is currently available so there will be some changes. I
will of course debug the new board.
c. Pulled the "new" 8-inch drive and carefully inspected it for
issues. Saw nothing obvious like a burned component, bad connector or
disconnected cable so there is an issue somewhere in the write chain.
Debugging the drive is almost impossible when it is installed in the
cabinet and I don't have the resources to do it outside the cabinet so
I will get another drive (found one on eBay). In the meantime I will
change the one that will not write to be the boot drive (A) and make
the fully functional drive A. That way my disk copy routines (CP/M or
DOS/65) and format routines will work better as most of them are set
to copy A to B or format B etc. Once I get the "new" drive and verify
it I'll see if the existing drive can be repaired.
Still a lot do do with the 5.25 inch drives but I am getting close to
having a stable system with two (mostly functional) 8-inch drives.
Motherboard itself is solid as are the other system components.