Home Page
Back to Home Page
1980s Computers Explanation of terms

The KIM-1

KIM-1 board


MOS Technology (US)
MOS were bought out by Commodore soon after the KIM-1 was launched.


(Keyboard Input Monitor)

Date Launched

April 1976



Microprocessor type

MOSTEK 6502 @ 1 MHz

ROM size

2 kilobytes

Standard RAM

1152 bytes

Maximum RAM

9 kilobytes with the standard KIM-1, or up to 65 kilobytes using a KIM-4 motherboard and KIM-3B memory expansion cards.
RAM cost £193 for a board holding 8 kilobytes.

Keyboard type

Calculator style hexadecimal keyboard with 23 keys

Supplied language

Machine code monitor

Text resolution

6 digit LED display.
It was possible to access each individual segment in the LEDs so that letters and other shapes could be produced.
The KIM-1 could also be connected to a teletype via a serial link, or a VDU interface to connect to a television was available for £150.

Graphics resolution

None other than setting segments in the LED display

Colours available


Example Screenshot

KIM-1 LED display
(Simulated) KIM-1 hexadecimal digit display.


Software could make square-wave beeps if an external speaker were fitted.

Cassette load speed

Normally about 50 baud but up to 800 baud was possible with extra software.
The monitor program also contained routines for saving and loading using punched paper tape.

Dimensions (mm)
Weight (grams)

180 x 235 x 20 approx.
Not known

Special features

A very cheap computer for its time.

Good points

Had 30 input/output lines for interfacing to external equipment. The KIM-1 was often used in laboratories for monitoring and control.

Bad points

Only a bare board was supplied, without even a power supply.
RAM was small and expensive to expand.
Programming was only possible in machine code.

How successful?

Quite popular with hobbyists and industrial users – seven thousand KIM-1s had been sold by August 1977.
Unlike many other early computers, a large number of programs were written for the KIM-1.


The KIM-1 was designed by Chuck Peddle of MOS Technology, the makers of the 6502 microprocessor, to demonstrate the microprocessor's industrial potential, but turned out to be a success in its own right.
The previous year MOS Technology had sold the TIM kit but this was supplied as just a schematic and monitor ROM; the buyer had to provide all the other components.
The Mark II version of the KIM became the Commodore PET.

Chronological listing
Back to chronological list
Home Page
Home Page
Next computer
Next computer

Hosted by www.Geocities.ws