21 May
2014
21 May
'14
12:45 p.m.
My 5150 had one spare ROM socket. I put in an
optional enhancement ROM
from MBI.
My 5170s did NOT have any spare ROM sockets. Or did you mean the sockets
used by the BASIC ROMs?
But, YES, many of my aftermarket XTs and ATs had extra sockets.
Or were there more variants of the 5170 motherboard than I was aware of?
There were at least 2 versions of the 5170 motherboard. The obbious
difference is the RAM. The older one has 4 rows (36 packages) of those
strange IBM piggybacked chips, a pair of 64K*1 DRAMs with slgihtly
different pinouts. The later version ahs 2 rows (18 chips) of 41256s
The later board i have has 4 EPROM sockets. There was also a DIP shunt
block associated with them at the very back edge of the board. I think
you could eitehr fit 16K byte of 32K byte EPROMS (4 of the former, 2 of
the latter) with the correct jumpering of that DIP shunt.
-tony