Prime Computer Inc’s scientific processing partner Cydrome Inc has been giving its Cydra 5 dataflow architecture machine its first viewing this week at the International Conference in Supercomputing in Santa Clara, California. The machine uses two types of system memory, controlled by the Motorola 68000 processor, one for rapid parallel access and the other for serial access; both use 1Mbit dynamic RAMs and can handle data and instructions. The former has been interleaved so that the numeric processor can access it in parallel over a 200Mbyte-per-second bus but the latter is accessed serially by the general processor over the system bus, which maintains longer access times but requires a greater bandwidth. The Cydra has 256Kb of parallel memory, extendable in 16Mb increments, and 8Mb, 16Mb or 32Mb serial memory. The numeric processor was specifically designed to make the Cydra 5 a number cruncher as well as a general purpose machine. It uses a 64-bit bus, rated at 100Mbytes-per-second and standard ECL and some Motorola gate arrays. Unlike other minisupercomputers the numeric processor in the Cydra has the same priority as general purpose processors. The numeric processor includes a 32Kb instruction cache but no data cache because Cydrome believes that it can degrade performance. Initially only one numeric processor will be included in the Cydra 5 but it is designed for multiple processors. The operating system is Unix System V.3 modified to run across multiple processors. The input-output processor is a 16MHz 68020 that can control up to three VMEbus interfaces. The Cydra 5 is said to be dataflow-like because unlike traditional dataflow machines it does sustain large overheads in scheduling data available for operations – normally dataflow hardware senses when inputs are available, tags them and performs two associative searches for each operation. The Cydra uses an intelligent compiler – its own implementation of ANSI Fortran 77 with DEC VMS and IBM Fortran extensions – to schedule operations rather than the hardware. The Cydra is aimed at owners of general purpose machines such as the DEC VAX that want more power for compute-intensive tasks. The Cydra 5 is expected to be available this summer for $600,000 to $900,000 both from Cydrome itself, and from its 10% shareholder, Prime Computer.
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