MOS Technology KIM-1

The MOS Technology KIM-1 was a compact, fully assembled single-board computer created to demonstrate the inexpensive 6502 processor. It included a hexadecimal keypad, six LED digits, monitor firmware, RAM, timers and accessible input/output connections on one exposed circuit board.

Users could program it directly in machine code, connect a terminal or cassette recorder and expand it into a more complete computer. Its low price and detailed documentation made the KIM-1 influential among hobbyists, educators and engineers during the first years of personal computing.

Notable Features

• The complete computer occupied one exposed circuit board and required only a regulated power supply to use its keypad and LED display.
• Two MOS 6530 devices supplied monitor ROM, RAM, timers and input/output alongside the 6502 processor.
• A cassette interface and serial terminal connection allowed programs and data to be entered or saved beyond the six-digit display.

Historical Significance

• The KIM-1 helped establish the 6502 among hobbyists and developers before the processor became central to many mass-market computers and consoles.
• Its accessibility encouraged early software including Peter Jennings’ Microchess and inspired compatible single-board systems.

Collector’s Notes

• MOS Technology, Commodore/MOS and later board revisions differ in markings and component details.
• Original manuals, keypad caps, power connector and cassette or terminal accessories add useful context; the exposed board should be handled carefully.

Specifications

Technical Information
Name	MOS Technology KIM-1
Manufacturer	MOS Technology
Launched	Thursday, January 1, 1976
Discontinued	Approximately 1981
Launch Price	$245
Country	United States
CPU	MOS Technology 6502 at approximately 1 MHz
Units Sold
Form Factor	Exposed single-board computer supplied fully assembled and tested
Power	+5V regulated supply required; additional supply requirements depended on expansions
Additional CPU	Two MOS 6530 RAM-I/O-Timer devices
Operating System	KIM monitor firmware; programs entered and run directly in 6502 machine code
Expansion / I/O	Application and expansion connectors with 15 programmable I/O lines, timers, serial terminal and cassette interfaces
Keyboard	Integrated 23-key calculator-style hexadecimal and control keypad
Storage	Audio cassette interface; programs could also be entered from the keypad or a terminal
Sound	No built-in sound hardware; software audio projects could use I/O lines
Colours	Red LED display
Graphics	Not applicable; hexadecimal LED display or external serial terminal
Display	Six hexadecimal seven-segment LED digits
ROM	2KB resident KIM monitor firmware in two MOS 6530 devices
RAM	1KB total, including RAM within the two 6530 devices
CPU Speed	Approximately 1 MHz