14 Oct
2010
14 Oct
'10
11:04 a.m.
On 10/14/10 1:43 PM, Ethan Dicks wrote:
The main board of a 7300/3B1 is on the bottom of the machine, and my
very vague memory from 20+ years ago says it might actually be
component-side down. If this is actually the case, it'd likely be too
tight in there for such a daughterboard.
-Dave
--
Dave McGuire
Port Charlotte, FL
On 10/14/10, Eric Smith<eric at brouhaha.com>
wrote:
Compared to the WD1010-based MFM controller it'd be replacing? ;)
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. 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. ;-)