On 10/06/2017 07:59 AM, Anthony Bennett via cctalk wrote:
Now here is the kicker. The 370 mainframes had swing gates with motherboards,
and each motherboard had a couple of logic cards with components soldered on
them.
In IBM terminology, those "motherboards" were called
"boards" and what plugged into them were "cards".
The cards had MST modules which were 1/2" square ceramic
substrates with the rough equivalent of one to two
MECL 10,000 chips. The MST modules had 22 pins. The boards
had up to 60 cards in them, but the cards were
quite small, about 1.5 x 4" for a single-wide, and 3 x 4"
for a double-wide. These could hold about 8 MST modules on
a single-wide, and about 16 on a double. So, a typical 370
had a fair number of these boards, and many hundreds of
cards. This was VERY small-scale integration. The chips in
the MST modules were just several gates or 2 FFs.
IBM had done their homework on interconnect reliability for
the 360, and applied what they learned in the 370, and so
they did not have big issues with that. The boards had
gold-plated pins, and the cards had selectively-plated gold
contact fingers that made contact to the pins. Interconnect
between the boards was done with festoons of "tri-lead"
which was
93-Ohm planar cable with a pair of ground wires flanking a
signal wire. These plugged in all around the edges of the
boards.
I tried to help a friend get a 370/145 running in his
house. A total fool's errand due to the power consumption.
Jon
