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Corvus (Mostek subsidiary)

Corvus Corporation was a subsidiary of Mostek Corporation of Dallas, Texas, U.S.A., a semiconductor manufacturer.

Mostek was founded in 1969 by people from Texas Instruments.  In 1970 it was struggling financially and contracted with the great Japanese pioneer calculator technology company Nippon Calculating Machine Co. (Busicom) to produce a single LSI chip for calculators.  After frenzied development work the first ever "calculator on a chip" was produced at the end of 1970, as told in "The Chip" archived from the Mostek site.  This integrated circuit was the MOSTEK MK6010 which was first used in the Busicom Junior/NCR 18-16 desktop calculator and also in the Busicom LE-120A "Handy", the first pocket-sized calculator.

Busicom Junior with calculator-on-a-chip
Busicom LE120A HANDY

the MOSTEK MK6010 calculator-on-a-chip in the Busicom Junior/NCR 18-16 desktop calculator.

the MOSTEK MK6010 calculator-on-a-chip was used to make the first pocket-sized calculator, the Busicom LE-120A "Handy".

Mostek went on to produce chips for other calculator manufacturers and for its own calculators from its Corvus subsidiary.  It became the major supplier of integrated circuits for Hewlett-Packard's scientific calculators and H-P soon became Mostek's largest customer.

HP35 circuit board

Mostek was a supplier to Hewlett-Packard for the integrated circuits in the HP-35, the first hand-held scientific calculator.

The chips in the ceramic packages and the metal cans in this HP-35 were manufactured by Mostek.

Mostek also manufactured and sold calculators through its Corvus subsidiary and under the Unisonic label[1].

Examples of Corvus calculators

Corvus 400

Corvus 400

A small 4-function calculator with red LED display.

Corvus CheckMaster

Corvus CheckMaster

Check (cheque) balancing calculator.  Only 2-functions, but retains the balance for up to a year.

This is a Featured Calculator.

More photographs of Corvus calculators can be found in the Photograph Library here.


Mostek Corporation, the parent company of Corvus, largely exited the calculator market in 1975 due to making large losses there, but retained just the CheckMaster, above, as reported in the journalElectronics[2].  "Rights to manufacture the calculator line, and to market under the Corvus label, went to Colex Ltd., Hong Kong", a long-time chip customer.  Mostek retained the digital clocks as well as a checkbook calculator, products it will market under the Mostek brand name."



  1. "Electronic firm cuts bait for fishermen", Electronics, September 27, 1973, pp34-35.
  2. "Mostek trims its sails", Electronics, June 12, 1975, pp70-71.

Vintage Calculators

Text & photographs copyright, except where stated otherwise, © Nigel Tout 2000-2024.