at&t unix pc

Ethan Dicks ethan.dicks at gmail.com
Thu Oct 14 12:43:49 CDT 2010


On 10/14/10, Eric Smith <eric at brouhaha.com> wrote:
> 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...

> There is plenty of I/O address space available.

Unsurprising (given 16MB of range), but good to have confirmed.

> Years ago I wire-wrapped a card with a 5380 SCSI chip.

That would be when I would start - and maybe consider a WD33C93 (as
found in the Amiga 3000) if the performance of the 5380 turned out to
be an issue.

> I never got to the stage of having a reliable driver.

Ah.  Out of curiosity, did you happen to write it from scratch or did
you have existing UNIX 5380 drivers to "borrow" from?

> A wire-wrap board won't fit into the computer itself; it took up three slots of an expansion box.

That can be addressed with a real PCB prototype, but I probably
wouldn't personally invest in a run of boards until driver issues were
addressed.

> 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.

That is unfortunate - enough to make the whole process difficult.
Perhaps a CPU-socket design is worth considering.  64 pin DIP sockets
are still available.  ;-)

-ethan



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