Before 1975, MITS was a struggling calculator manufacturer when its founder, Ed Roberts, decided to develop a low-cost hobbyist computer. The Altair 8800 saved the company and generated $5 million in sales during its first year. But in 1977, Roberts sold the company to Pertec, and its fortunes soon declined. Pertec discontinued all Altair lines in July 1978. Triumph Adler bought what was left of the company from Pertec.
Bill Gates saw an opportunity when the Altair 8800 appeared on the cover of the January 1975 issue of Popular Electronics magazine. In short order, he left his studies at Harvard and joined MITS, where he wrote the BASIC used in the system. The Altair 8800 is perhaps the most important early microcomputer. It was the first mass-produced micro, and with BASIC a hobbyist could program it for a wide range of tasks. Its Altair Bus was based on the IEEE 696 standard for connecting expansion boards to the main CPU board, better known as the S-100 bus.
Best of all, it was affordable with prices starting at $439. MITS offered upgrade options ranging from memory to I/O interfaces, through which hobbyists could use cassette storage devices and printers. Some 5,000 units sold in the first year, which encouraged other vendors such as Processor Technology to develop software and hardware for the Altair. In short, the Altair 8800 was the first practical, highly expandable, and affordable microcomputer. As you might guess, the Altair 8800 is a highly sought-after collectible. Although they were produced in relatively large numbers, locating a working unit in good cosmetic shape is difficult.
The early 8800s were unreliable and had weak power supplies. An 8800a version followed shortly that fixed many of the design and construction shortcomings. However, it wasn’t until the Altair 8800b was released that MITS had a relatively bullet-proof system. The 8800b had an updated CPU board and a ROM-driven front panel.
The 8800b Turnkey Model appeared in June 1977. It had a plain front panel with a lock and two switches. With the system locked, continuous operation for control applications was ensured. An 8800b model similar to the original 8800 was also available. Altair 8800b systems tend to sell for 10 to 15 percent less than comparable 8000 units, while the Turnkey units sell for half the amount or less.
The Altair 680 was smaller than many other systems of the day due to a design philosophy of keeping it simple. It was considered an easy-to-build kit, with most of the circuitry on one PC board. Three configurations were available: a full front panel model with all addressing, processor, and data entry controls; a turnkey model with only the control for restarting the ROM software–used in dedicated applications to minimize operator error; and a single board model that could be used as a core in other systems. The front panel had its own circuitry to control the processor–reset, halt, or start. MITS later introduced an Altari 680b, which had a serial interface and more expansion options through the 680b-MB Expander Card.
MITS Altair 8800/8800b (March 1975 /1976 [8800b], early micro)
Original Retail Price: $439 kit, $621 assembled
Base Configuration: 8080 CPU; 16 S-100 slots; 1K RAM (64K max); status LEDs; front-panel switches; assembly, operations, and theory manuals, expander board, aluminum enclosure, power supply
Important Options: Altair DOS, 88-DCDD or 88-DISK floppy disk drive, cassette interface, Comter or Altair VLCT terminal, 88-2SIO serial and 88-4PIO parallel interfaces, Altair BASIC or Extended BASIC, Altair 110 Line Printer
MITS Altair 680/680b (Dec. 1975 /1976 [680b], early micro)
Original Retail Price: $345 kit, $420 assembled
Base Configuration: 6800 CPU; S-100 bus; 1K RAM; front panel switches; RS-232 or Teletype interface; monitor in ROM; assembler; debugger; editor; assembly, operation, and theory manuals
Size/Weight: 11 x 11 x 5 inches (680b)
Important Options: PROM storage, Altair 680 BASIC