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Royal Digital IV
Display is 8 digits, red LED.
4-function.
Main integrated circuit - General Instruments GI 251 (here date coded 7206).
7.2 v (6 x AA rechargeable cells).
81 mm x 165 mm x 39 mm (3.2" x 6.5" x 1.6").
Introduced late 1971/early 1972.
Made in U.S.A. This example "Made in USA for Imperial Typewriter Company Limited, Leicester, England".
From the magazine "Electronics", Jan. 3rd, 1972 -
"Royal Consumer Products division, Hartford, Conn., a part of Litton Industries. With its Digital III and IV, made by the Monroe division of Litton, Royal is in a position
to market these units to consumer outlets, from mass merchandisers to the corner stationery shop. With quantity discounts and prompt payment, dealers get these machines for under $90. Suggested retail prices are $139 and $149
[about £58 & £62 Sterling]."
Price in UK, June 1972, £52-50.
Royal, Imperial Typewriter, and Monroe were all part of the Litton Industries empire.
At this time calculator keyboards were complicated and expensive components. To cut this cost this calculator shows gold-plated pads on the circuit board
through the front of the calculator. Touching a pad with the electrically connected stylus has the same effect as pressing a key on a standard calculator.
Only the Royal Digitial III and Digitial IV are known to have this stylus feature.
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