Posted on Feb 6, 2014

Programmed Signetics 8223 256-bit PROM is used as alphameric display having five 7-segment digits connected to form alphameric simulation of abbreviations for second, millisecond, microsecond, hertz, kilohertz, and megahertz as SEC, SEC-3, SEC-6, H2, H2 3, H2 6. Binary counter U3, 4-16 line decoder, and 5-digit parallel-connected Hewlett. Packard d

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isplay form simple multi-plexer that addresses memory U4 one word at a time. External 1000-Hz square-wave oscillator drives counter and sets scanning rate. Requires only one 5-V supply. Article gives truth table for memoryand circuit for programmer required to set it up J. W, Springer, Function/Units Indicator Using LED Displays, Ham Radlio, March 1977, p 58 63.

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