Chapter 44 ½The CRAY-1 Computer System 745
Table 1 CRAY-1 CPU Characteristics Summary
Computation Section
12.5 nanosecond clock period operation
64-bit word size
Integer and floating-point arithmetic
Twelve fully segmented functional units
Eight 24-bit address (A) registers
Sixty-four 24-bit intermediate address (B) registers
Eight 64-bit scalar (S) registers
Sixty-four 64-bit intermediate scalar (T) registers
Eight 64-element vector (V) registers (64-bits per element)
Vector length and vector mask registers
One 64-bit real time clock (RT) register
Four instruction buffers of sixty-four 16-bit parcels each
128 basic instructions
Prioritized interrupt control
16 independent banks of 65,536 words each
4 clock period bank cycle time
1 word per clock period transfer rate for B, T, and V registers
1 word per 2 clock periods transfer rate for A and S registers
4 words per clock period transfer rate to instruction buffers (up to16 instructions per clock period)
Each channel group contains either 6 input or 6 output channels
Each channel group served by memory every 4 clock periods
Channel priority within each channel group
16 data bits, 3 control bits per channel, and 4 parity bits
Maximum channel rate of one 64-bit word every 100 nanoseconds
Maximum data streaming rate of 500,000 64-bit words/second
Channel error detection
are used to store an 8-bit check byte required for single-bit error
correction, double-bit error detection (SECDED).
Data words are stored in 1-bank increments throughout memory. This
organization allows 16-way interleaving of memory accesses and prevents
bank conflicts except in the case of memory accesses that step through
memory with either an 8 or 16-word increment.
Cooling System
The CRAY-1 generates about four times as much heat per cubic inch as the 7600. To cool the CRAY-1 a new cooling technology was developed, also based on Freon, but employing available metal conductors in a new way. Within each chassis vertical aluminum/stainless steel cooling bars line each column wall. The Freon refrigerant is passed through a stainless steel tube within the aluminum casing. When modules are in place, heat is dissipated through the inner copper heat transfer plate in the
module to the column walls and thence into the cooling bars. The modules are mated with the cold bar by using stainless steel pins to pinch the copper plate against the aluminum outer casing of the bar.
To assure component reliability, the cooling system was designed to provide a maximum case temperature of 130° F (54° C). To meet this goal, the following temperature differentials are observed:
Temperature at center of module
Temperature at edge of module Cold plate temperature at wedge Cold bar temperature Refrigerant tube temperature |
130° F(54° C) 118° F(48° C) 78° F(25° C) 70° F(21° C) 70° F(21° C) |
Functional Units
There are 12 functional units, organized in four groups: address, scalar, vector, and floating point. Each functional unit is pipelined