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Altair 8800b microcomputer released by Micro Instrumentation and Telemetry Systems (MITS) in June 1976, with the manufacturer's label applied to the rear reading: “MITS ‘Creative Electronics,’ Serial No. 5401672K.” The computer, 17˝ x 7˝ x 17.75˝, features a total of 25 address, input, and control switches to the front panel. Included is an ADM-3A video display terminal manufactured by Lear Siegler and released in 1976. The manufacturing label to the reverse reads: “Model No. ADM3A, Part No. A3ACD0000000, Serial No. 531936.” The Altair 8800b is confirmed and tested to be fully functional and in working condition; the case bears scattered scuffs and marks.
The Altair 8800b, the second computer in MITS’ 8800 series, is a general-purpose, byte-oriented (8-bit) machine that ran Altair BASIC—Microsoft’s first commercial product. It uses a common 100-pin bus structure that supports expansion via standard or custom plug-in modules. The system can accommodate up to 64K of directly addressable memory and can address up to 256 separate input and output devices. The 8800b implements 78 basic machine-language instructions and is built around a power supply board, interface board, CPU board, and display/control board.
Several enhancements distinguish the 8800b from its predecessor. Five new front-panel switch positions were added to expand control and monitoring capabilities: Slow, Display Accumulator, Load Accumulator, Input Accumulator, and Output Accumulator. The CPU board features an Intel 8080A microprocessor and an Intel 8224 clock running at 2 MHz. Additionally, the original Altair 8800’s four-slot expander cards were replaced by a single 18-slot motherboard, which provides the full 100-pin bus via 100 solder lands.
The ADM-3A was a low-cost ASCII ‘dumb’ video terminal widely used as a console for minicomputers and early microcomputers like the Altair. It featured a 12-inch monochrome CRT displaying 24 lines by 80 columns, connected to a host via an RS-232-style serial interface and configured with DIP switches for baud rate and parity. Implemented with TTL logic rather than a microprocessor, it simply interpreted characters and control codes from the host. The ADM-3A became especially popular in hobbyist and academic settings, and its keyboard—famously labeled H, J, K, and L with arrow symbols—influenced the vi editor’s cursor-movement keys.
