Sinclair Cambridge Programmable
Sinclair Cambridge Programmable
Radio Shack EC-4001
Sinclair Cambridge Programmable / Radio Shack EC-4001.
Display is 8 digits, red LED (made by National Semiconductor).
Scientific programmable.
Integrated circuits - National Semiconductor MM5799EHY/N and DS7784N, here date coded early 1977.
9v (PP3 battery) - a "pregnant" model, see photograph below.
50 mm x 111 mm x 28 mm.
Made in England.
The Radio Shack EC-4001 model was supplied by Sinclair to the U.S. 'Radio Shack' chain of electronics stores, a division of Tandy Corporation.
The back of the Sinclair EC-4001 calculator, showing the 'pregnant' bulge of the battery compartment, enlarged to take a 9v PP3 battery rather than the AAA pen-cells that the Cambridge casing had been designed for.
This bulge drastically affects the aesthetics of the pregnant models and the practicality of using them on a desk.
The rear of the Radio Shack EC-4001 showing the 'pregnant' bulge and, on the left, the shaped tray which was supplied to support the calculator when used on a desk.
The calculator sitting in the shaped tray.
Thanks to Douglas Mendez for providing the photographs of the Radio Shack EC-4001 and tray.
Inside showing the National Semiconductor MM5799EHY/N and DS7784N integrated circuits.
Sinclair Cambridge Programmable dwarfed by the program libraries supplied for it. These are:
- Vol. 1 - General, finance, statistics.
- Vol. 2 - Mathematics.
- Vol. 3 - Physics & engineering.
- Vol. 4 - Electronics.
Sinclair models
Vintage British Calculators
Text & photographs copyright, except where stated otherwise, © Nigel Tout 2000-2024.