The Prototype Kenbak-1 Computer, 1971

Copyright 2007 by John Blankenbaker

Editorial note 2022: This is the original website of John Blankenbaker. Since 2022 maintained by Achim Baque - more information.
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The First Personal Computer.

KENBAK-1 Computer

The Kenbak-1 computer was judged in 1987 by the Boston Computer Museum to be the first commercially available personal computer. Initial sales commenced in September of 1971. Most units sold for $750.00 for a completely assembled and functioning computer. The computer was a stored program, automatically sequenced unit.

Designed before microprocessors were available, the logic consisted of small and medium scale integrated circuits mounted on one printed circuit board. MOS shift registers implemented the serial memory. Switches keyed the input and lights displayed the output. The memory contained 256 bytes and the computer executed several hundred instructions per second.

The computer was intended to be educational. Professionals in the field were enthusiastic but it was a struggle to convince the non-professionals that they could buy a real computer at this price.

The prototype computer above first operated in the spring of 1971 and was demonstrated at a high school teacher's convention. This machine still operates and was demonstrated in October 2005 at Montana State University. Production machines differed slightly in style from the prototype but had the same instruction set and performance.

The creator of the Kenbak-1 Computer was John Blankenbaker who is writing these notes.

Revised 26 February 2010