Executive - Vintage Sinclair

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Executive

Calculators

The Sinclair Executive was launched in August 1972 at a price of 79.95 + vat. It was the first true 'pocket' calculator, previously calculators were definitely desktop and required mains power.
The advertising claimed it was as thick as a cigarette packet and for once this was an understatement. It was attractively styled and it won it's designer Richard Torrens, the Design Council Award for Electronics in 1973. It was even  exhibited in the Museum of Modern Art in New York.

Functionally it was very limited, with and 8-digit display and just add, subtract, divide and multiply functions. It had automatic squaring, reciprocals and a choice of fixed or floating decimal points. The Integrated circuit at it's heart was the Texas Instruments GLS 1802, a Metal Oxide Semiconductor (MOS) with 7000 transistors.

Size : 56 mm x 138 mm x 9 mm (2.2" x 5.5" x 0.4").

At least two versions were produced with different keyboard layouts.

The big technical challenge was battery life as the LED display was very power-hungry. To get around this, clever circuitry was employed to cycle the power on and off very quickly, keeping the average power consumption down. Power is only turned on in 1.7 microsecond bursts, and when shut off, the capacitance of the chip maintains the data between cycles. Even so, battery life was only a few hours.

The Executive was a major success and made Sinclair about 1.8m in profits.

Type 1


Type 1
Slim profile. On/Off switch is on the side.


LED Display

Type 2

Executive Memory

In 1973, Sinclair followed up on the success of the Executive with the Executive Memory.
It had a distinctive black-and-white styling and sold at the cheaper price of 24.95.

It was the same size as the basic Executive model and used the same battery life-extending method of pulsing the electronics. It had 4 functions + memory.

A less common type 2 model was produced in black and with a gold coloured keyboard.

Black and white Type 1 version.


 

There was a Type 2 version of the Executive Memory produced, the only difference being the appearance.
The Type 2 had the all-black case of the non-memory version, and additionally, each key was inset with gold-colored metal.
These are much less common than the Type 1 model.  

 
 
 
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