The NWT (Numerical Wind Tunnel) computer system available at the NAL since February 1993 comprises two system administrators, n processing elements (where n was 140 at the beginning, and is 166 at present) and a crossbar network, and operates as a distributed-memory message-passing MIMD (Multiple Instruction and Multiple Data stream) computer. Each processing element itself is a vector computer. This paper reports measurements of two pairs of the characteristic parameters, (tau(sub infinity), n(sub 1/2)) and (tau(sub infinity), s(sub 1/2)), of the NWT with SIMD (Single Instruction and Multiple Data stream) computing on a single processing element and with MIMD computing in the local memory access, respectively. Furthermore the significance of the obtained results is interpreted, and several hardware parameters are estimated. The obtained results in this paper apply only to the NWT system software during the period April to June 1993 after which substantial improvements have been achieved with the NWT performance.
The characteristic parameters of the NWT computer system in the local memory access
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