Altair 8800
From Retrocomputing Wiki
| Altair 8800 | |
|---|---|
| Manufacturer | MITS |
| Type | Kit computer |
| Released | January 1975 |
| Introductory price | US$397 (kit), $498 (assembled) |
| Discontinued | 1977 |
| CPU | Intel 8080 at 2 MHz |
| Memory | 256 bytes standard, up to 64 KB |
| Storage | Paper tape, cassette, 8-inch floppy disk (later) |
| Display | Front panel lamps; serial terminal optional |
| Sound | None |
| Operating system | None built in; Altair BASIC, Altair DOS, CP/M |
The Altair 8800 is a microcomputer designed in 1974 by MITS (Micro Instrumentation and Telemetry Systems) of Albuquerque, New Mexico, and sold from early 1975 as a kit and as an assembled machine. It was the first microcomputer to sell in large numbers, and is widely seen as the spark that started the personal computer industry. It also gave Microsoft its first product.
Contents |
[edit] History
MITS was a small company run by Ed Roberts that had made model rocket telemetry kits and then electronic calculators. By 1974 the calculator business was being crushed by large chip makers, and the company was deeply in debt. Roberts decided to build a computer kit around Intel's new 8080 processor, which he was able to buy in quantity for $75 each, far below the list price.
The Altair appeared on the cover of the January 1975 issue of Popular Electronics, which went on sale in December 1974. The magazine's technical editor, Les Solomon, had been looking for a computer project to publish. The machine on the cover was actually an empty mock-up, as the only working prototype had been lost in shipping. MITS had hoped to sell a few hundred kits in total; it received orders for several thousand within the first months, and struggled for most of 1975 to deliver them.
In 1977 MITS was sold to the Pertec Computer Corporation, which dropped the Altair name within about a year.
[edit] Design
A basic Altair has no keyboard, no screen and no storage. It is a blue and grey box with a front panel of toggle switches and red LEDs. Programs were entered one byte at a time by setting the switches to a binary value and flipping the "deposit" switch, and the result was read off the lights. The standard machine came with only 256 bytes of memory.
Inside, the computer is built from plug-in cards on a backplane with 100-pin connectors. This bus was copied by many other manufacturers, and in 1976 it was renamed the S-100 bus. Cards were soon available from other companies for memory, serial and parallel ports, video displays and disk controllers, and an expanded Altair could be a genuinely useful computer.
[edit] Software
In early 1975 Bill Gates and Paul Allen wrote a BASIC interpreter for the Altair without having access to one, using an 8080 simulator running on a PDP-10 at Harvard. Allen flew to Albuquerque to demonstrate it, loading it from paper tape, and it worked the first time. MITS licensed it as Altair BASIC, and Gates and Allen set up their company, then called "Micro-Soft", to sell it. Allen became MITS's Director of Software.
Altair BASIC was widely copied by hobbyists who did not want to pay MITS's price for it, which led to Gates's well-known "Open Letter to Hobbyists" in early 1976.
[edit] Influence
The Altair was shown at the first meeting of the Homebrew Computer Club in March 1975, and many of the club's members went on to build their own computers or start companies. One famous early demonstration was by Steve Dompier, who wrote a program that made the Altair play "The Fool on the Hill" through the radio interference picked up by a nearby transistor radio.
Clones and compatible machines followed quickly, most notably the IMSAI 8080. Original Altairs are now valuable collector's items.
[edit] See also
- MOS Technology 6502, the much cheaper processor that appeared later in 1975
- Apple II
- TRS-80
