by Ian Matthews of Feb 15, 2003  Last Updated Nov 26 2018

MOS KIM-1 History


Rare White Commodore MOS KIM-1

In August 1974 eight Motorola employees including Bill Mensch and Chuck Peddle quit and went to work for a small chip manufacturer named MOS Technologies. By June of 1975 they had developed samples of the now legendary 6502 processor and needed a system to demonstrate it’s power.

The problem was that until they could produce a demonstration unit to show industry what the 6502 could do, they were limited to selling very small quantities of the chip directly hobbyists.  They charged just for just US$25 (adjusting for inflation that is  $110 in 2018) at a time when its functionally reduced competitor, the Motorola 6800 was selling for $200 (which is $900 2018 dollars).


April 1976 Byte Magazine Advert for the KIM1

In 1976 MOS designed and manufactured that needed demonstration computer.  It made history with the worlds first single board computer: the KIM-1.  Of course it used the 6502 (clocked at 1 Mhz) and it came with 1K RAM, built in ROM, hex keypad, 7 character LED display, 15 bidirectional input/output ports and a cassette interface (for storage!).  All of these components came fully assembled on a the KIM-1’s 9″ x 10″ board although it did not ship with a power supply.  They sold for $245 ($1100 2018 dollars).

KIM is an acronym that stands for Keyboard Input and Monitor.  Monitor in this case does not refer to a screen display like we have today.   Monitor refers to the VERY basic software that allows a user to see what is in memory.

Commodore bought MOS in the summer of 1976 and slightly re-branded the MOS KIM-1 to a COMMODORE KIM-1.

Over a short period of time, it became apparent to enthusiasts and corporations that the KIM was more capable than originally intended.  Instead of being used just a basic training device, companies were using it to control mechanical machines like factory equipment and Universities were using it for ‘real education’.

Note that it takes about 1K of RAM memory to fill a single 25 line x 40 character screen with text so MOS KIM-1 was indeed a very limited computer.

commodore-pet-2001-blue-lablel-chicket-keyboard-100-150MOS / Commodore did not produce a second version of the KIM-1.  The KIM board was redesigned and enhanced to become the worlds first personal computer, the Commodore PET, which included good looking metal chassis, calculator keyboard, integrated cassette storage, and internal power supply.

Commodore KIM-1 Derivatives

An important side note is that in 1978 Rockwell International introduced a slightly expanded version of the Commodore KIM-1 as the AIM65 for USD$375 ($1350 dollars in 2018).  If you are familiar with the AIM65, you may think the name came from the computer including Advanced Interactive Monitor (AIM) with a Commodore 6502 CPU.  The AIM was a very simple piece of software allowing the user to assemble binary, view and set memory.  However, AIM is an acronym that stands for Advanced Interactive Microcomputer.

rockwell-aim65-and manualThe AIM-65/40 was released in 1981 with a 40 character LED display for home and small business enthusiasts.  An industrial version was named the System 65 included such advanced features as a plastic housing, floppy drives and a PROM burner.

In parts of Europe AIM65’s were assembled and distributed by Spains Comelta.  They produced the Comalta Drac-1 and further enhanced the AIM65 to include their own plastic chassis and two eight inch floppy disk drives.

All versions were compatible with the original MOS/Commodore KIM-1.

Historic Importance of the KIM-1

The MOS Commodore KIM-1 was the worlds first computer assembled into just one board and was also the only computer Commodore allowed to be manufactured by other companies.

Commodore KIM-1 Brochures

As you can see in this 4 page  brochure, MOS went on to develop expansion boards such as:

  • KIM-3: 8K Memory Expansion Module
  • KIM-4: Motherboard: to interface with up to 6 other boards
  • KIM-5: Resident Assembler/Editor: to enter, edit and store assembly language programs

Commodore KIM-1 Schematics Manuals and Projects

Rockwell AIM-65 MANUALS

Commodore KIM 1 Magazine Articles

  • Is the KIM1 for Every1 – The Computerost 1976 – PDFWeb Page
  • Where is the KIM1 Going? – Kilobaud 1977 – PDFWeb Page
  • Computer Performance of Music -Byte 1977 – PDF

Commodore KIM-1 Photo Gallery

Commodore KIM-1 Videos



Marco M D · April 20, 2021 at 10:11 am

Hi, is it possible to know the exact capacity and type of capacitors that are used in the KIM-1?
Unfortunately some of my KIM-1 capacitors are starting to leak, so when the time comes I may have to replace them. Thanks for any reply!

Bob Leedom · October 14, 2020 at 9:13 am

In the olden days, I wrote a program called KIM-Venture. Like the classic Adventure game, KIM-Venture starts at a stream in a forest, and then requires that you find your way into a house and collect items that will be needed to explore the caverns. Once underground, you must get by obstacles, retrieve treasures, discover how to use a magic word for certain kinds of movement, and bring the treasures back to the house. All those facts are common both to the full-blown game and to KIM-Venture. In this mini-version, there are two dozen different locations to explore, a number of secret markings to interpret, five objects to be used in various ways, two animals (a bird and a dragon), and two treasures to retrieve. All of these — rooms, items, and animals, plus informative messages — are spelled out on the KIM-1 display.
Seems a shame to let this bit of KIM-1 history vanish. Any idea how this could be archived for future KIM enthusiasts to explore and enjoy?

    Ian Matthews · November 14, 2020 at 3:15 pm

    Hi Bob;

    If you can get us a digital copy, we can post it on our downloads page. I would hate to have it gone too.

Commodore PET and CBM | Low End Mac · May 1, 2018 at 5:30 pm

[…] home computers, there were hobbyist computers. The KIM-1 was one of the first, developed as a way for MOS Technology to demonstrate its 6502 CPU. The KIM-1 […]

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