IMSAI 8080
Announced:August 1975
How many:Around 20,000
Price:US $931 assembled
US $599 as a kit
CPU:Intel 8080A, 2.0 MHz
RAM:64K max
Display:front panel LEDs
Controls:front panel switches
Expansion:card-cage w/ S-100 bus
Storage:optional cassette or
floppy drive
OS:CP/M, BASIC





IMSAI was started by William Millard in 1972, as IMS Associates (Information Management Sciences) - a computer consultancy and engineering company - providing engineering and software management to mainframe users including business and government. The services they offered were very advanced.

In 1974 they obtained a contract with Philip Reed to develop an automobile accounting system. Once completed, it was functional, but it was expensive and needed too much maintenance. Reed wanted a better system - he had an automobile dealership - his intention was to sell it to other dealerships.

IMS would have just bought and utilized the newly released Altair 8800 computer, but Altairs were difficult to get in a timely manner - their supply couldn't keep up with the demand.

So IMSAI did the next best logical thing - they designed and built their own computer system! Technically, it was just an improved copy of the Altair 8800 system - IMS even advertised the interoperability - but it was more professional and better looking. This is when they changed their name to IMSAI Manufacturing Corporation.

Released in 1975, first as a kit, then as a fully-assembled system, their new IMSAI 8080 computer became very popular, and sold for many years. The kit version was hundreds of dollars cheaper, but it took many long days of careful soldering and assembly to create a (hopefully) working IMSAI.

In its simplest configuration with only a CPU (Central Processing Unit) card, you enter your program using the front panel switches, while reading the results on the LED indicator lights. No keyboard or other display is necessary. This type of programming is very slow and tedious - any mistake could corrupt the system and you'd have to start over again. Only true hackers were successful at efficiently operating an IMSAI 8080.



Like all early S-100 based systems, the IMSAI is really just a large metal case with a power supply, and numerous slots to insert the expansion cards. But due to the limitless expandability afforded by the S-100 bus design, an actual keyboard, monitor, printer, data storage, and other peripherals can all easily be added to make this a very useful system.

Some call the IMSAI the first clone of another computer system, in this case, of the MITS Altair 8800, a similar computer which was release just a few months earlier. It will even accept the same cards as the Altair, because of the S-100 bus design. The IMSAI was not the only computer to copy MITS' S-100 bus scheme, but it was the first.


In an effort to expand into the serious business market, the IMSAI VDP-80 (Video Data Processor) was released in 1977. It is a large and heavy all-in-one computer system.
In 1978, IMSAI released the slightly smaller VDP-40 systems.

This was the true beginning of the computer age. In September 1975, the very first issue of BYTE magazine was issued. On the cover they proudly state: "Computers: The worlds greatest toy!".


Fans of the movie Wargames may remember seeing the IMSAI 8080. Look for it next time you watch!

Related Links

  • IMSAI pre-history mirror from www.landley.net
  • The official home page of IMSAI
  • "When PCs Were Micros" from rwebs.net


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