website/content/museum/imsai-8080.md

---
title: IMSAI 8080
categories:
- Computers
types:
- Home Computer
origins:
- U.S.A.
years:
- '1976'
cpus:
- Intel 8080A
params:
  name: '8080'
  image: /media/museum/photos/imsai_8080_1.jpg
  company: /companies/imsai
  company_name: IMSAI
  specs:
  - label: NAME
    value: '8080'
  - label: MANUFACTURER
    value: IMSAI
  - label: TYPE
    value: Home Computer
  - label: ORIGIN
    value: U.S.A.
  - label: YEAR
    value: Start of 1976
  - label: BUILT IN LANGUAGE
    value: None
  - label: KEYBOARD
    value: None, front panel switches are used to program the system
  - label: CPU
    value: Intel 8080A (rarely 8080)
  - label: SPEED
    value: 2 MHz (each instruction takes 4 clock cycles)
  - label: RAM
    value: 256 bytes
  - label: ROM
    value: Unknown
  - label: TEXT MODES
    value: Depending on the video terminal used (optional 64 x 12 card)
  - label: GRAPHIC MODES
    value: None
  - label: COLORS
    value: None
  - label: SOUND
    value: No speaker in the case
  - label: SIZE / WEIGHT
    value: Unknown
  - label: I/O PORTS
    value: I/O port
  - label: BUILT IN MEDIA
    value: None
  - label: OS
    value: Unknown
  - label: POWER SUPPLY
    value: Buit-in power supply unit
  - label: PERIPHERALS
    value: S-100 cards
  - label: PRICE
    value: $439 kit, $621 assembled (1976) - $599 kit, $931 assembled (1977)
  tabs:
  - photos
  - adverts
  - hardware
  - emulators
  - links
  photos:
  - title: IMSAI 8080
    subtitle: ''
    text: ''
    image: /media/museum/photos/imsai_8080_front_2.jpg
  - title: FRONT PANEL
    subtitle: ''
    text: ''
    image: /media/museum/photos/imsai_8080_front_3.jpg
  - title: BACK
    subtitle: ''
    text: ''
    image: /media/museum/photos/imsai_8080_back.jpg
  - title: COMPLETE SYSTEM
    subtitle: ''
    text: |-
      Complete system including:\
      \- A dual 8" F.D.D unit from Digital Systems\
      \- A serial video terminal.

      IMSAI 8080 could use the **Tarbell** Floppy Disk Interface to connect up to 4 F.D Drives (243 KB each - 250 Kb / second).\
      Controller chip was a Western Digital 1771.\
      Operating system vas a modified CP/M
    image: /media/museum/photos/imsai_8080_system_1.jpg
  - title: IMSAI8080 WITH FLOPPY DISK DRIVE
    subtitle: ''
    text: picture courtesy of Yellowchoo Ebay seller
    image: /media/museum/photos/imsai8080_withdiskdrive.jpg
  - title: INSIDE 8080
    subtitle: ''
    text: |-
      Inside this 8080 case, one finds:

      **(1)** A processor card\
      **(2)** Four memory cards\
      **(3)** Three Input/Output and peripherals cards\
      **(4)** Power supply transformer and condensers
    image: /media/museum/photos/imsai_8080_inside_1.jpg
  - title: POWER SUPPLY
    subtitle: ''
    text: ''
    image: /media/museum/photos/imsai_8080_powersup_1.jpg
  - title: MANUAL
    subtitle: ''
    text: ''
    image: /media/museum/photos/imsai_8080_manual_1.jpg
  - title: THE TARBELL CASSETTE INTERFACE
    subtitle: ''
    text: This interface can be used with IMSAI or ALTAIR. It transfers from 187 to 540 bytes / second.
    image: /media/museum/photos/tarbell_k7.jpg
  - title: THE IMSAI 750
    subtitle: ''
    text: I don't know exactly what is this computer. Surely the successor of the IMSAI 8080.
    image: /media/museum/photos/imsai4.jpg
  adverts:
  - title: 1977 ADVERT
    subtitle: ''
    text: |-
      The advert said :

      Waiting for you, all the incredible performance and power of the IMSAI 8080. And at a price you would normally pay for a home music system : $699 in kit, $931 assembled...

      **WORLS OF USES :** The IMSAI 8080 is a superbly engineered, putting litterally hundreds of applications and uses at your fingertype...

      **GROWS WITH YOU :** The IMSAI 8080 is designed for many years of pleasure. With its open-chassis engineering, you can expand your system by adding peripherals and interfaces. The 22 slots and 28 amperes power supply mean that you can plug-in todays's plus tomorrow's modules. Right now, you can add a module for displaying color graphics and characters on TV, a ready-to-use keyboard, a cassette tape recorder, small and large printers...

      **EASY TO PROGRAM :** With our BASIC language, you can operate the IMSAI 8080 quickly and easily. Thechnically knowledgeable ? Use our assembly language to develop sophisticated and unique software.
    image: /media/museum/pubs/imsai_8080_pub_1.jpg
  - title: BYTE SHOPPER
    subtitle: ''
    text: Spring 1978 issue of Byte shopper guide
    image: /media/museum/pubs/imsai_8080_byteshopper_s1.jpg
  - title: POWER... IS EXPENSIVE!
    subtitle: ''
    text: |-
      The Megabyte Micro was a special version of the Imsai made with 16 x 64 KB RAM boards (Imsai just introduced this card) and a control board called Intelligent Memory Manager. A mapping configurator allowed each user to use its own protected RAM area.

      Prices :

      64 KB RAM board Kit: **$2599**, assembled: **$3899**\
      Intelligent Memory Manager board: **$299**, assembled: **$399**

      To note: in 1977, 1 MB RAM costed... $62384!
    image: /media/museum/pubs/imsai_8080_pub_2.jpg
  - title: NOT REALLY AN IMSAI!
    subtitle: ''
    text: |-
      In october 1979, the IMSAI company went bankrupt. The IMSAI brand name and the spare parts stock were sold to the **Fischer-Freitas** Company.

      This 1982 advert shows a Z80 CP/M based computer Fisher-Freitas tried to sell with the IMSAI name, without success.

      Fisher-Freitas is still selling original parts for the 8080 model! and continue maintaining a nice 8080 history web site (see the Web links section).
    image: /media/museum/pubs/imsai_8080_pub_3.jpg
  - title: ADVERT FROM NEW ZEALAND
    subtitle: ''
    text: |-
      In November 1976, the assembled basic version cost A$931, the unassembled version cost A$599.

      Thanks to **Murray Moffatt** from New Zealand
    image: /media/museum/pubs/imsai_8080_pub_s4.jpg
  hardware:
  - title: F.D. SYSTEM
    subtitle: ''
    text: |-
      Advert (March 1977) said:

      The North Star Micro-Disk System uses the Shugart minifloppy disc drive. The controller is an S-100 compatible PC board with on-board PROM for bootstrap load. It can control up to three drives. With the PROM bootstrap, we provide our powerful extended Basic (10 Kb) with sequential and random disk file accessing.\
      Each 5'' diskette has 90k data byte capacity. Basic loads in less than 2 seconds.

      Micro-Disk system (kit) **$699**\
      Micro-Disk system (Assembled) **$799**\
      Additional drive **$425**\
      Diskette **$4.5**
    image: /media/museum/hardware/altair_8800_fd_1.jpg
  - title: ADVERT DATED SEPTEMBER 1976
    subtitle: ''
    text: |-
      \- PROM board\
      \- TV Dazzler video card\
      \- Analog I/O board\
      \- Cyclop optical digitalizer
    image: null
  - title: US ADVERT (1977)
    subtitle: ''
    text: You could use these joysticks with the Altair or any S100 bus system. They connect to the Cromenco D+7/A I/O board and were meant to play the games available for the Cromenco TV Dazzler, the first video card for personal computer.
    image: /media/museum/hardware/cromenco-joysticks_pub_1-1977.jpg
  - title: ADVERT (NOVEMBER 1976)
    subtitle: ''
    text: ''
    image: null
  emulators:
  - title: Altair and IMSAI Emulators
    url: http://www.threedee.com/jcm/emu8080/index.html
    platform: Windows
    text: Altair 8800b and the IMSAI 8080 emulators for Windows
  - title: Altair32 Emulator Project
    url: http://highgate.comm.sfu.ca/~rcini/classiccmp/Altair32.htm
    platform: Windows
    text: Windows emulator based on the original emulator of Claus Giloi
  links:
  - title: IMSAI.NET
    url: http://www.imsai.net/
    text: Where you can buy a 20 Mhz. Z80 version of the 8080!
  - title: oldcomputers.net
    url: http://oldcomputers.net/imsai8080.html
    text: Nice page with beautiful pictures
  - title: When PCs where Micros
    url: http://rwebs.net/micros/Imsai/Default.htm
    text: Nice original IMSAI brochure put on the web
  - title: www.obsoletecomputermuseum.org
    url: http://www.obsoletecomputermuseum.org/imsai/
    text: nice detailed IMSAI page
  comments:
  - author: GOplayer (USA)
    date: Wednesday 19th September 2018
    text: |-
      I was lucky enough to buy the IMSAI 8080C computer at a computer business that had an auction after the owner passed away for $14. ! It works great but I couldn''t bid on the two 8"floppy drives because the $14. was all I had! I begged the auctioneer afterwards for the drives as they didn''t sell, but he wouldn''t relent... My unit needs 3 switch covers(orange/blue) as I accidentally knocked them off... I have them somewhere. The computer is immaculate and works as if new,(love the robustness of older technology electronics). One big TO-3 voltage regulator(5V?) on the back wall on a aluminum 90 degree fin in front of the fan and two big capacitors(electrolytic) in the front in the voltage supply area on the right, walled off by aluminum shield from the S-100 bus slots on the left. The CPU is white w/gold cap. Such a joy to see it operate on the front panel as I load address and data registers(8 bit)using the switches in single step load/review mode. Then I flip then switch for Run and toggle the start switch and watch the digital light show as it computes, branches, adds and moves REAL Binary Data around before I hit the start/stop toggle switch or it reaches a halt in the program. I need to make a digital video of it in action someday. It is still a joy to operate, setup, run and observe the data in red Light Emitting Diodes(LEDs). This was one of the first times we could SEE our data bits and computing in action.

      I was a programmer in the Air Force on 64-bit machines in the early 70''s... COBOL, PL/1, RPG, FORTRAN and assembly.

      This machine is a museum piece that STILLl functions as it was designed. I had a few Timex Sinclair''s as well. Also great inexpensive machines for their day. Clive Sinclair was a mathmatician and it is reflected in the tight byte codes of his BASIC language computers for the masses. They are great as 8/16 bit scientific BASIC computers, not just for gaming, which is fun, and drove the computing industry to where it is today.

      Steve Ingham 9-19-2018
  - author: Lorno (Calgary, Canada)
    date: Saturday 12th November 2022
    text: I bought my IMSAI 8080 as a kit back in 1976. By 1979 I had it feeding a Heathkit H9 terminal and was running Northstar Basic. Writing and running Basic Code LOL. Everything is still downstairs in my basement in boxes, although I havent fired them up since 1983.
  - author: Edward Kenny (Huntsville, AL USA)
    date: Thursday 29th September 2011
    text: I used a couple of IMSAI 8080''s at NASA in the early 1980''s. Each had a Z80 4MHz CPU and 64KB of RAM. For storage each had a dual set of 8-inch floppy drives. Each also had a 5MB hard drive but were never used much because they were not very reliable and eventually failed.
  - author: Fubeca6
    date: Saturday 21st August 2010
    text: Raindance Rob - it was indeed used in War Games (check out Fire in the Valley by Paul Freiberger and Michael Swaine)
  - author: Raindance Rob (UK)
    date: Saturday 31st July 2010
    text: looks like what David played by Matthew Broderick used in the film Wargames, can anyone confirm ?
  - author: Thomsonicus (Poland!)
    date: Wednesday 17th January 2007
    text: now that's what I call oldschool! Respect to all who have been using this piece of fine equipement
  - author: ian osgood (Portland, OR)
    date: Thursday 4th March 2004
    text: I learned BASIC and 8080 assembly as a wee lad on one of these. It was owned and tricked out by a housemate, Gail Marshall. He wrote his own keyboard drivers and graphics libraries (so he could do the Game of Life) as well as an implementation of LISP. He hacked an Olivetti daisy-wheel typewriter into a printer! Gail was truly a Real Programmer. We still have a box of 8" disks around somewhere...
  related:
  - /museum/mits-altair-8800
  oc_id: 389
  source:
    url: https://web.archive.org/web/20230328234541/http://www.old-computers.com/museum/computer.asp?c=389
    date: '2023-03-28'
---

After seeing the instant success of the MITS [ALTAIR 8800](/museum/mits-altair-8800/) computer, the first "home computer" ever made, others soon tried their luck in this new business space. One of the first to do so was Bill Millard who founded IMS Associates.

The computer they designed, the IMSAI 8080, was very similar to the Altair 8800 and was designed to run the same software. However, it was a much better design, with a higher specification power supply, an anodized aluminum chassis, 22 slots on the S-100 bus, and a great front panel design.

The IMSAI 8080 aimed to take advantage of the Altair's popularity, the inability of MITS to meet a growing demand for the product, and the need to improve on some of the internal components. Like the Altair, the IMSAI came either in kit form, or preassembled at the factory.

At the production starting, the IMSAI was shipped deliberately missing many parts in the kit version, because the company hadn't received them yet. But since IMSAI promised delivery by a certain date, they shipped them anyway!

Like the Altair system, there were no keyboard but a front panel and switches used to program the system. The LED's blinked, depending of the values found on the address and data buses. One could manually stop the CPU, single step the CPU, and read and write to memory locations.

In the end, the IMSAI outlasted the Altair by several years. Owners were delighted to see it featured in the 1984 movie "War Games", with Matthew Broderick and Ally Sheedy. Through the years, it has remained a much-beloved design amongst vintage computer collectors, and newly-manufactured parts and documentation are still available! (see Web links)