Cray CRAY-1 - Modules; Clock

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There are 1662 modules in a CRAY-l with a standard 16-bank
'
memory. Modules
are arranged 72 per chassis as illustrated in figure 2-2. There are over ~/
115 module types. Usage varies from 1 to over 700 modules per type. Module
type and usage is summarized in Appendix B. Each module type is identified
by two letters. The first indicates the module series (A, 0, F, G, H, J, M,
R, S, T, V, X, and Z). The second letter identifies types of modules within
a
series.
The computation and I/O modules are on the eight chassis forming the center
four columns. Each of the eight chassis on either side of the four center
columns contains one of the 16 memory banks.
Modules are cooled by transferring heat via the heat transfer plate to
cooling bars
which in turn transfer the heat to a refrigerant-22. Power
dissipation depends on module density. The average module dissipation by
usage is approximately 50 watts.
Two supply voltages are used for each module: -5.2 volts for IC power;
-2.0 volts for line termination.
Each module has 96 pin pairs available for interconnecting to other modules.
All interconnections are via twisted
pair wire. The average utilization of
pins is approximately 60 percent.
Each module has 144 available test points that can be used for trouble
shooting. Test points are driven
by circuits that do not drive other loads.
CLOCK
All timing within the mainframe cabinet is controlled by a single phase
synchronous clock network. This clock
has a period of 12.5 nsec. The
lines that carry the clock signal from the central clock source to the
individual modules
of the CPU are all made of uniform length so that
the leading edge of a clock signal arrives at all parts of the CPU
cabinet at the same time. A three nanosecond pulse (figure 2-3) ;s
formed on each module.
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2-4
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