The BINAC was a bit serial binary computer designed by Eckert-Mauchly. It had a 512-word acoustic mercury delay line memory divided into 16 channels each holding 32 words of 31 bits with an additional 11-bit space between words to allow for circuit delays in switching. The clock rate was 4.25mh which yielded a word time of about 10 microseconds. The actual instruction execution rate was dominated by the access time for instructions and data and would have averaged about 3000-4000 instructions per second, unless minimum latency programming was employed. Each BINAC word held two instructions. Each instruction had a five bit operation code and a three octal digit address. All operands were 31-bit words. Arithmetic was two’s complement and there were single-bit arithmetic right and left shift instructions as well as addition, subtraction, multiplication and division. There were no logical instructions and no subroutine calls. Jump on negative was the only conditional instruction. The BINAC was the first dual processor computer, and was built for the U.S. Navy.
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