>The whole reason Cray's are wired up as circles rather than linearly like a
>mainframe is to reduce wire lengths (and with them speed of light delays).
Although I never looked at the prints for one, all of the Cray 1's that I
had a chance to examine were not completely circular--there was always a
wedge missing.
I expect this was almost essential; all of the wiring between circuit
cards was on the inside of the circle, and the customer engineers had to be
able to get to that wiring.
I suspect that the reason Seymour Cray built the machine in the shape he
did was that the circuit cards, plus the machined columns that supported
and cooled them, were wider than the card connectors. By arranging the
card columns in a semi-circle with the connectors on the inside, he could
minimize wiring length.
----
John Dykstra jdykstra_at_nortel.com
Principal Software Architect voice: +1 651 415-1604
Nortel (Northern Telecom) fax: +1 612 932-8549
Received on Tue Oct 20 1998 - 09:56:02 BST