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The IMSAI 8080

Manufacturer IMS Associates (IMSAI)
Model 8080
Date Announced 1976
Date Canceled Early 1980s
Number Produced Tens of thousands
Country of Origin USA
Price $400+ for the kit, $600+ assembled, to start.
Current Value $500 and up
Processor Intel 8080
Speed 2 MHz
RAM 256 bytes and up. Usually at least 8K
ROM None. PROM could be added
Storage Paper Tape, Cassette tape, disk drives (8" or 5.25")
Expansion Up to 22 slots
Bus S-100
Video Terminal based or various optional video cards.
I/O Serial, Parallel, etc.
OS Options CP/M, NorthStar DOS and many others.
Notes The IMSAI 8080 is often considered to be the first "clone" computer. Although the developers had a machine in the planning stages at the time they reacted to the success of the MITS Altair 8800 and followed its bus specification. In the end, the IMSAI was far more successful than the Altair and the company lasted longer. A vestige still exists today at IMSAI.NET.
Related Items in Collection Sol 20, MITS Altair 8800, CompuPro S-100 System and a variety of other S-100 and CP/M systems.
Related Items Wanted IMSAI drive subsystem (floppy and hard drive) - IMSAI VDP and 8048 systems. Additional software and docs.

The IMSAI 8080 was probably the first clone in the PC world. The unprecedented success of the MITS Altair prompted many to enter the Personal Computer arena with competing systems to capitalize on the new market and MITS inability to fulfill all of its orders in a timely fashion.

The IMSAI 8080 gained further fame when it stared in the 1984 film, War Games, alongside Matthew Broderick and Alley Sheedy.

The interior of the IMSAI 8080

The inside of this 8080 case is as clean as the day it was built. Only about half of the 22 slots on the motherboard are populated.

The IMSAI Processor Board

The IMSAI processor board running an Intel 8080A.

Problem Solver Systems 16K RAM board.

One of the IMSAI's RAM boards, a Problem Solver Systems 16K unit.

Bytesaver II

The Cromemco Bytesaver II was a popular PROM board capable of holding 8 PROMS and burning new data onto them.

Processor Technology VDM 1

The Processor Technology VDM-1 was one of the first ever video boards.

CUTS Tape Card

CUTS was another Processor Technology Product capable of driving a cassette tape deck for program and data storage.

This IMSAI System came with a nearly complete set of documentation, pictured below.

The IMSAI 8080 Manual The CUTS Basic Manual The CUTER manual Processor Technology BASIC Manual The ALS-8 manual Cassette Tapes with IMSAI Software

The IMSAI also came with a couple of program tapes including ALS-8 and BASIC. These have not yet been tested.

IMSAI Keyboard

And finally, the IMSAI came with a nice parallel keyboard in spite of the fact that it doesn't have a Parallel card installed.

(Submitted June 25, 2011 13:06:52 by GreenMeanie)

Need an Imsai and drives for my Computer Website.

(Submitted February 24, 2011 20:08:26 by David Johnson)

I have an Imsai 8080 with 56K RAM, North Star disk controller, dual 5 1/4 disks, homebrew disk controller for 8 drives, Rom card, serial/par I/O card, and others. Would like to sell. Running when moth-balled.

(Submitted January 15, 2010 20:16:07 by gmeanie)

I am still looking for an imsai and also imsai disc drive setup.

(Submitted April 24, 2009 11:09:23 by (a href=mailto:)Mortar(/a))

I was a fan of the 8080, not because of its capabilities but because of HOW it did things. Back in those days I was pretty new to computers and the 8080 LOOKED like a computer, with all the switches and light. I had a ball playing with that thing, even though I didn't really know what I was doing.

(Submitted December 22, 2008 15:43:05 by (a href=mailto:gclouseATclearwireDOTcom)Gary Clouse(/a))

Back in 1970 Tennesse Tech University had one in the Math department. It had been assembled by one of the math professors, who mis-wired some dip headers that configured the the add on serial card. and I got volunteered to make it work by a friend. What the photos can't show is how heavy the compute was. I picked the computer up from the a cart to move it to a desk, while it was plugged in with the cover off, and in the process, my right thumb hit the ac power , causing me to drop it on my left foot, resulting in a minor injury that has ever since made me unable to curl my left big toe. Anyway, I had it working in no time and talking to a decwriter III in the math lab vi 60 mA current loop serial connection.

(Submitted December 19, 2008 19:02:54 by Gerry)

Bought my IMSAI in September, 1976 for $651. I toggled programs in through the front panel for awhile, then bought an ASR-33 teletype. When Tarbell introduced their mag tape interface, I bought one.

I had a question about my tape drive and decided to call Tarbell. A man answered the phone and when I asked who I was speaking with, the answer was, Don Tarbell.

Those were the days.

(Submitted September 27, 2007 08:43:19 by Bill Cowley)

I have an IMSIA-8080 in my basement all boxed up. I think I have a pair of 8 inch floppy drives also. I may still have a set of hard drive for it. I have an ASR-33 TTY. Several manuals, boxes of software, paper tapes, tarbell board. All this stuff worked and then I switched over to something called an IBM. I'm a EE and now live in St. Louis MO area. I'm sure this stuff has value to someone. Contact me at

(Submitted September 14, 2007 08:57:32 by greenmeanie)

I need the Imsai IKB-1 keyboard,Imsai FDC-2 floppy drive, and electrohome 17 monitor. Email me with what you have.

(Submitted September 13, 2007 12:05:47 by greenmeanie)

I am loking for an imsai and altair for my collection. email me with what you have.

(Submitted August 16, 2007 01:44:28 by Chris Johnston)

It was around 1977 - I was still in high school and worked part time as a bench tech for a company called Computer Mart of Orange (Calif). I must have assembled over a hundred of the machines and gazillion of those Seal's 8K ram cards. Got the soldering technique down to about an hour a board.

George Tate was my boss then - he went on to form Ashton/Tate (if that rings a bell for you).

I will never forget one time getting the polarity reversed on one of the filter caps on the power supply. The thing went off like a BOMB after a day of idling. Punched a hole in the ceiling insulation.

the 8080 was a remarkable CPU - you could get CPU state on the M1 clock - made for an interesting display.

(Submitted August 4, 2007 14:32:42 by Walt Perko)

Having recently bought a semi-working IMSAI 8080 on eBay I'm looking for help understanding how to set the RAM 4A memory card address switches since I have three of these cards ???

(Submitted November 12, 2006 13:11:26 by Joe Killian)

Well, memory fades with time. Poking around I tripped across a reference by a New York City dealer on the first IMSAI shipment being December '75. That does indeed ring a bell, getting the first batch out (just) in time for Christmas. So I rescind my earlier comment (only) with regards to our 1st shipment being January '76. Joe

(Submitted November 12, 2006 11:33:40 by Joe Killian)

The IMSAI 8080 was announced sometime late summer or early fall 1975. Orders started arriving at that time. The first shipment was Jan. 1976. Early 1975 we had asked MITS for fast delivery of an Altair & quantity discount to fill our need for a contract we were working on. They declined without comment on both counts. We figured it was still the right solutin and I proceeded to design our own similar machine. That summer, seeing how the microcomputer market was taking off, I persuaded owner Bill to place a small classified ad in Popular Electronics. When orders and checks started arriving, we partnered with our customer, dropped their development project, and concentrated on finishing and shipping the IMSAI 8080.

(Submitted August 11, 2006 16:23:35 by Dave Brandt)

I got the optical paper tape reader with an assembler...later Microsoft 12K Basic. Tried the casette thing, not too good, switched to 8 double-sided Sugart [sp] drives ... just like in 'War Games', the movie. By the time IBM came out with their PC I was at 8086/87 10-MHz with 64K and two 40-MB haed drives.

(Submitted May 5, 2005 13:29:20 by Dale Chatham)

You've got the date wrong on these. I bought mine in 1975 as I remember it.

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