Next up in Rochester Electronics’ series of favorite 1970s semiconductors, is the Hewlett-Packard 5082-7000 Solid-State LED-based Numeric Indicator. Although this device was created in 1969, we have chosen to include it with our historic semiconductors of the 1970s, as it was only in the early 70s that it became established and led to follow-on devices. These devices eventually came to dominate the numeric display market and displaced the existing technologies, such as the Nixie Tube.

The visible LED (Light Emitting Diode) was invented in 1962 by Nick Holonyak, while working for General Electric Co, and the discrete LED had already been adopted for use in a variety of applications. In the late 1960s, Hewlett-Packard used its background in LED technology, along with its capabilities in manufacturing, packaging, and solid-state semiconductors, to develop an integrated numeric display. The integration simplified its implementation and opened its use across multiple designs.

The compatibility of the integrated display, along with the developing use of integrated circuits, led to its wide adoption, not only in Hewlett-Packard’s products but also with many other equipment manufacturers and applications. Interfacing was straightforward with direct compatibility to 5V TTL (transistor-transistor logic) and DTL (diode-transistor logic) logic ICs. The display could accept a 4-line BCD (binary coded decimal) input and decode it to display the digits 0 to 9.

The ease of use of the interface’s design was not its only advantage. Readability, durability, and manufacturability were also significantly improved. The displays provided high contrast and wide view angles, and utilized a separate input for the LED power source. This provided an easy method to adjust the brightness based on the applications and the ambient conditions. The technology also lent itself to high-volume manufacturing. The LEDs and display’s overall construction provided a more ruggedized device and a longer lifespan than the existing technologies.