Altair 8800
The Altair 8800 from MITS (Micro Instrumentation and Telemetry Systems) was the first mass-produced personal computer to be openly available. It was introduced in January, 1975, as a kit; later, pre-assembled units were made available.
It was a microcomputer, built around an Intel 8080 microprocessor. The early 8800's were unreliable, and had a weak power supply; the later 8800a was better, but it was only with the 8800b that it became really reliable. It originally came with no peripherals, just a front panel; later, a variety of optional add-on units, including a floppy disk drive, were made available.
It is famous for being the machine that got Bill Gates and Paul Allen started; MITS did a deal with them to write a BASIC interpreter for it (Allen was actually hired as a MITS employee).
The Altair 8800 was implemented as a set of cards (ex: a CPU card, a memory card, optional serial or disk controller cards, etc) connected by a 100-pin backplane. Both MITS and third-party companies produced cards using this bus. This 100-pin Altair bus led to the standardization of the S-100 bus, which is very similar, but not 100% compatible.
