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Re: S-100 Motherboard


Thanks - I will probably do that after looking at the signals on the
scope and trying the 74LS14.

An update on testing.

I had previously stated that the floppy subsystem has two eight inch
SSSD drives. Well, that is not quite accurate. When first built in
1983 (?) I had two Shugart 801 drives. One failed several years ago
and when I pulled the failed drive to get it repaired I operated with
just a single 801 (in 800 mode of course) for years. Removing or
installing a drive in the Vector cabinet is no easy feat given size
and weight of cabinet with it's power supply and the weight of the
drives themselves as well as the cramped access to the three
connectors (50-pin edge, 3 pin AC, and 6 pin DC) that need to be

Yesterday I upwrapped the replacement 801 that had been sitting on the
shelf for years and after a lot of setting and double checking of
jumpers actually installed it as drive B.

It was a partial success. It reads fine but would not write either
normally or when formatting. So I need to pull it and check for
problems. I will probably start with another check of jumpers although
I think that is unlikely. More likely might be a cable issue with the
write protect sensor. In any event that probably won't happen until
tomorrow so no update is likely until tomorrow.

If I can not determine a cause I may have to leave it out permanently
as I am not sure there is anyone either repairing the nearly 30-year
old drives or that has operational drives for sale.