at&t unix pc

[Eric Smith]

Ethan Dicks wrote about the AT&T Unix PC (7300 or 3B1):
> I don't presently have one, but if I do ever run across one, I'd want
> to make sure I had a "StarLAN" card (1Base5, for the pedants in the
> crowd) - I even have a few official StarLAN transceivers and such -
> they work fine on a 10BaseT network.
>    
StarLAN does *NOT* operate on a 10BaseT network.  The signalling is 
similar, but the data rate is 1 Mbps rather than 10 Mbps.  StarLAN 
generally will not work with 10, 10/100, or 10/100/gig hubs or 
switches.  There may have been some networking equipment that could 
interoperate with both StarLAN and 10baseT, but I've never found it.

For the Unix PC, there were separate cards for StarLAN and for 10 Mbps 
Ethernet.  The StarLAN card used the Intel 82586 Ethernet MAC chip, 
while IIRC the 10 Mbps Ethernet card used the AMD Am7990 "LANCE" 
Ethernet MAC chip.  The 10 Mbps Ethernet card did not include a 10baseT 
transceiver, but one can be connected via AUI.

I don't know anything about the StarLAN software for the UnixPC.  The 
Ethernet card came with a port of the BSD IP stack done by The 
Wollongong Group.  Because the kernel is System V Release 2, they had to 
implement select() in a user space library, and it ONLY works with 
network sockets, and not with native devices.  This makes it challenging 
to get any non-trivial networking software ported.

Eric