at&t unix pc

[Eric Smith]

Ethan wrote about the AT&T Unix PC (7300 or 3B1):
> It makes one wonder then how hard it would be to rig up a card with a
> Lance chip (7990) and either IDE or SCSI - I know there are "memory
> expansion" slots, but don't know how finicky the machine might be
> about borrowing some of that address space for I/O (or if the slots
> could decode regions already _in_ I/O space).
There is plenty of I/O address space available.

Years ago I wire-wrapped a card with a 5380 SCSI chip.  I never got to 
the stage of having a reliable driver.  A wire-wrap board won't fit into 
the computer itself; it took up three slots of an expansion box.

One impediment to making cards for the Unix PC is that the 99-pin 
three-row DIN-style connector is no longer made.  If I remember 
correctly, one actually needs some of the contacts at both ends, but 
perhaps one could butcher two 96-pin DIN 41612/IEC 60603-2 connectors 
into a single 99.  I haven't studied the mechanical drawings of the 
connectors to figure out how much the connectors would need to be hacked.

Eric