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The Cray Computer Corporation Cray-2

Machine type: Shared-memory multi-vectorprocessor.
Models: Cray-2.
Operating system: UNICOS (CCC's Unix variant).
Compilers: Fortran, C.

System parameters:


The Cray-2 is the system that was developed by Seymour Cray and was the precursor of the Cray-3 and Cray-4.

The Cray-2 contains a foreground processor which performs system tasks, I/O handling, and synchronisation of the background processors, the vectorprocessors proper. The number of background processors which do the actual computational work is 1--4. The clock cycle is 4.1 ns.

A main bottleneck in the Cray-2 is that there only is one port to main memory per processor where the memory itself is relatively slow. This requires at least a high data re-use to minimise the memory traffic but this is not helped at all by the inability of the CPUs to chain operations.

The Cray-2 was often was bought mainly for the (then) large memory of 4 GB. In the Cray-2 machines a local memory is present in every background processor, more or less used as a cache memory, and not accessible from a high level language. Library routines, using the local memory could greatly improve the performance in many cases.
Tue Nov 14 15:39:09 PST 1995