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1980s Computers Explanation of terms

The Kenbak-1



Kenbak Corporation (US)


From the designer's surname

Date Launched

September 1971


Not sold in the UK

Microprocessor type

The Kenbak-1 predated the invention of the first microprocessor (the Intel 4004 of November 1971).
The Kenbak therefore used numerous (132 in total) separate logic chips to build up the functionality of an 8-bit CPU.
The clock oscillator ran at 1 MHz.

ROM size


Standard RAM

256 bytes of serial memory

Maximum RAM

Not known

Keyboard type

No keyboard
Input was via a row of pushbuttons on the front panel.

Supplied language

The Kenbak-1 was programmed in binary machine code.

Text resolution

Output was a row of lights on the front panel.

Graphics resolution

Not applicable

Colours available

Not applicable



Cassette load speed

No tape interface

Special features

Often considered to be the first stored-program personal computer.

Good points

Allowed users to have a taste of the basic principle of computer programming.
Had a stylish pressed steel case.

Bad points

There was not a great deal you could do with just a line of lights as output.

How successful?

About 40 were sold in total. Kenbak Corporation closed in 1973.


Designed by John V. Blankenbaker.
Despite the relatively fast clock speed the program execution speed would have been much slower, only a few hundred instructions per second.
This was because the Kenbak-1 used serial memory rather than true random-access memory. Memory locations could only be read in sequence so that several hundred memory accesses would typically be needed before the wanted location came around. The 'microprocessor' registers were also held in serial memory so all register access would have suffered from this delay too.

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