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Compucorp 320 Series

Compucorp produced several series of advanced calculators.  Shown here are members of the 320 series of scientific calculators.
They are:

Sumlock Compucorp 324G Scientist

Sumlock-Compucorp  324G

Sumlock-Compucorp 324G Scientist

Distinctive features: One of a series of sophisticated calculators.  This model has scientific functions and is programmable, able to store two 80-step programs.  Battery powered though rather large for a hand-held calculator.

Technical details:
Display: 12 digits, amber 'Panaplex II' gas discharge.

Power supply: 4x D size rechargeable cells.

Functions: Scientific programmable (can store two independent 80-step programs).

Main integrated circuits:
Board 1) Texas Instruments TMC 1864NC, TMC 1871NC, General  Instruments 8KR029, 8KR03A, Intel 4x 2102, AMD 3x 93L0059X.
Board 2) Texas  Instruments TMC 1866MC, TMC 1867NC, TMC 1870, TMC 1872NC.
Board 3) Texas Instruments TMC 1869NC, TMC 1884NC.
The latest date code in the machine illustrated is week 32 of 1973.

Size: 140 mm x 230 mm x 70 mm (5.5" x 9" x 3"), 1100 g (2.5 lbs.) without batteries.

Manufacture: Made in the U.S.A. and sold by Compucorp, Computer Design Corporation, Los Angeles.
Compucorp supplied these machines as the OEM to Monroe in the U.S.A., Sumlock in Britain, and IME in Italy.

This machine is badged 'Sumlock', a trade name of the British company Sumlock Anita Electronics Ltd..


This is one of a series of machines for different purposes.  The journal 'Electronics', for December 6, 1971, on their introduction, said of this series of calculators[1]
"Each machine is 'microprogramed' with MOS/LSI logic specifically for each application.  ROMs produced by Texas Instruments and AMI to Compucorp specs control the keyboard functions pre-programed by the  manufacturer.  Groups of calculators bearing family names such as Statistician, Scientist, Accountant, and Treasurer, are thus tailored to the user."

Significance: This series of high-quality, high-function, calculators looked very futuristic when they appeared with their smart and business-like design.  Inside, a great deal is squeezed into a small volume, yet everything comes apart and goes back together very easily for servicing.  The functionality of each machine in the series "is 'microprogramed' with MOS/LSI logic specifically for each application".

Although these models can be powered by the internal rechargeable D-size batteries, their large size makes them rather a handful for a hand-held calculator, and they are perhaps more accurately called 'portable' calculators.

Within a couple of years the IC manufacturers where cramming all of this functionality into 1 or 2 ICs, the cost of the competition plummeted, and the size shrank.

Inside Sumlock-Compucorp  324G

Here the keyboard and assembly of circuit boards has been removed from the casing.  The four circuit boards plug into a stack of sockets, on the right, which acts like a miniature backplane and also mounts the display.

Components of Sumlock-Compucorp  324G

The circuit boards have been unplugged from the stack of sockets to reveal the number of large integrated circuits required at this time to produce a scientific programmable calculator.

Label of Sumlock-Compucorp  324G

The rear label, showing the high power consumption of 1.3 Amps at 7 Volts, and the label for servicing through the British distributor Sumlock Anita Ltd.

IME Compucorp 322G Scientist


IME-Compucorp 322G Scientist

Technical details:
Functions: Scientific programmable (can store a single 80-step program).

Similar to the Compucorp 324G, above.

Badged for IME (Industria Macchine Elettroniche) of Italy.

Note that this example is missing the shade over the display.

Sumlock Compucorp 320G Scientist


Sumlock-Compucorp 320G Scientist

Technical details:
Functions: Scientific, non-programmable.

Similar to the Compucorp 324G, above.

This machine is badged 'Sumlock', a trade name of the British company Sumlock Anita Electronics Ltd..

Looking very similar, Compucorp also produced the 340 series of Statistican calculators, the 360 series of Bond Trader/Financial calculators, and the 354 Surveyor calculator.


For an excellent account of the history of Compucorp see Rick Bensene's site at http://www.oldcalculatormuseum.com/d-compucorp.html, and for more technical details of some Compucorp machines see John Wolff's site at http://www.johnwolff.id.au/calculators/Compucorp/Compucorp.htm.



  1. Walker, Gerald M., 'Calculators that do more, sell more', Electronics, December 6, 1971, pp106-107.

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