Sumlock-Compucorp 324G Scientist
Display is 12 digits, amber Panaplex gas discharge.
4x D size rechargeable cells.
Programable (two 80-step memories).
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.
140 mm x 230 mm x 70 mm (5.5" x 9" x 3"), 1100 g (2.5 lbs.) without batteries.
Made in the USA., and sold in Britain under the Sumlock name, and in the U.S. and elsewhere under the Monroe name or just Compucorp.
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 -
"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."
Although the models in this series 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.
These high-quality programmable 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.
Within a couple of years the IC manufacturers where cramming all these functions into 1 or 2 ICs, the cost of the competition plummeted, and the size shrank.
For an excellent account of the history of Compucorp see http://www.oldcalculatormuseum.com/d-compucorp.html
Here the keyboard and assembly of circuit boards has been removed from the casing. The circuit boards plug into the assembly of sockets, which acts as a backplane and also mounts the display.
The circuit boards have been unplugged from the socket assembly to reveal the number of large integrated circuits required at this time to produce a scientific programmable calculator.
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.
© Text & photographs copyright Nigel Tout 2000-2018 except where noted otherwise.