Royal Digital III & IV




Home > Hand-held Calculators

	Royal Digital III and Digital IV

		Royal Digital III



	Royal Digital III Distinctive features: Low-cost hand-held calculator, achieved by eliminating normal keys and having only a 4-digit display. Technical details: Display is 4 digits, blue individual vacuum fluorescent tubes. Calculations are actually performed to 8 digits and the display can be swapped between the high 4 digits and the low 4 digits using the "<->" key. 4-function. Is operated by touching the circuit board through the windows in the casing using the stylus. Main integrated circuit - General Instruments GI 250 (here date coded 7208). 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. by Royal Typewriter Company, Hartford, Conn.

With the cover removed to reveal the circuit board with the gold-plated stylus contact areas.

The main circuit board carries the calculator integrated circuit and the four display tubes. The base of the calculator holds a pack of six AA size rechargeable cells.


		Royal Digital IV



	Royal Digital IV Distinctive features: Low-cost hand-held calculator, achieved by eliminating normal keys. Technical details: Display is 8 digits, red LED. 4-function. Is operated by touching the circuit board through the windows in the casing using the stylus. 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.



		With the cover removed to reveal the circuit board with the gold-plated stylus contact areas and the LED display.





	The main circuit board carries the calculator integrated circuitwhile the base of the calculator holds a pack of six AA size rechargeable cells.

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.