SI ABBREVIATION DISPLAY

Description: The programmed Signetics 8223 256-bit PROM is utilized as an alphanumeric display featuring five 7-segment digits, which are interconnected to simulate abbreviations for units of measurement such as seconds, milliseconds, microseconds, hertz, kilohertz, and megahertz, represented as SEC, SEC-3, SEC-6, H2, H2 3, and H2 6. A binary counter (U3) and a 4-16 line decoder are employed alongside a 5-digit parallel-connected Hewlett-Packard display, forming a simple multiplexer that accesses memory (U4) one word at a time. An external 1000-Hz square-wave oscillator drives the counter and establishes the scanning rate. The circuit requires only a single 5-V power supply. The article includes a truth table for the memory and a circuit diagram for the programmer necessary for setup.

The Signetics 8223 256-bit Programmable Read-Only Memory (PROM) is designed to facilitate the display of various time and frequency units through a series of five 7-segment displays. Each display is capable of presenting alphanumeric characters, which allows for the representation of common abbreviations used in measurement contexts. The configuration of the displays enables the simulation of units such as seconds (SEC), milliseconds (SEC-3), microseconds (SEC-6), and frequency measurements in hertz (H2), kilohertz (H2 3), and megahertz (H2 6).

The core of the system includes a binary counter (designated as U3), which is instrumental in generating the necessary timing signals for the display. This counter operates in conjunction with a 4-16 line decoder, which translates the binary output from the counter into a format suitable for driving the 5-digit Hewlett-Packard display. The combination of these components forms a multiplexer, allowing the memory (U4) to be accessed sequentially, one word at a time.

To ensure accurate timing and refreshing of the display, an external 1000-Hz square-wave oscillator is incorporated into the design. This oscillator not only drives the binary counter but also sets the scanning rate for the display, ensuring that the visual output is updated in a timely manner. The entire circuit operates on a single 5-V power supply, simplifying the power requirements and enhancing the overall efficiency of the system.

Additionally, the associated article provides a truth table that details the operational states of the memory, as well as a circuit diagram that outlines the programming setup required to initialize the PROM for specific applications. This comprehensive design allows for flexibility in usage across various measurement scenarios, making it a valuable tool in electronic display applications.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 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.