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Calculators: Handheld: Commodore Minuteman 3 Metric
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Size (approx): | 75mm
(max) x 105mm x 27mm (max) (w,h,d) Weight 96g excluding batteries |
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Power: |
6.0V DC, internal rechargeable battery. Accepts an adapter/charger (6V DC 200mA) through top side socket in the middle. Adapter should be 3mm positive centre. | ||
| Case: | Lovely palm-sized white matt two-piece plastic calculator. The upper area is dominated by a black painted metallic panel which is silver printed with conversion guides, switch label and raised CBM logo. A red, slightly tilted but flush plastic display filter with flat LED digits gives a bright easily viewed image. The keyboard is surrounded by a black plastic panel. The keys are squishy but positive enough. Sticking with the red white and blue key colour scheme this compact calculator just oozes quality. Useful conversion guide on the back panel as well. | ||
| Display: | 8 digit LED with no lens, ninth digit for minus sign and error flags | ||
| Features: | Four function plus percentages, four function memory and conversion functions. | ||
| Age: | 1974 | ||
| Manufacturer: | Made in England. Serial No. 020086 | ||
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Comments:
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The minuteman series was a great concept for sturdy handheld calculators. The display was a lovely flat LED; the vertical bars being made up of four dots. The (CE) key acts as a function key (Conversion Entry) to change the operation of a number of keys - very confusing. Would it be a little cynical of me to suggest that this was a good way of saving money by not having a custom key labelled (CONV) perhaps? Original case is stiff brown plastic with flip over top and popper closing. Very similar to another Minuteman 3 Metric (type II). |
| Components: | 1 x cpu: MOS MCS 2521A006
0174 (date code week 1 of 1974), 26 pin DIL, 0.6" width 2 x chips: One Texas SN75492A M7413 (week 13 of 1974) and one ITT 4S1 7352 (week 52 of 1973) display drivers both 14 pin DIL, 0.3" width 1 x nine digit red LED display 1 x transistor 3 x diodes 3 x resistors (one joined between the battery pack and adapter socket) 5 x capacitors 1 x transformer |
| Boards: | Main CPU board is is soldered to the keyboard assembly underneath by 13 wires. It has the reference numbers PCB 300148, ART 300349B, ASSY 300350. A 17-way ribbon connector joins to the display. |
| Construction: | Remove the two screws on the back and gently prize the calculator's rear away from the front. The battery floats but all the boards are attached to the front. |
| Logic comments: | (C) cancels an incorrect numerical entry, pressing a second time clears the calculator |
| Confusingly (CE) stands for Conversion Entry. | |
| To convert imperial to metric: (1)(0)(CE)(0) converts 10 inches into centimetres | |
| To convert metric to imperial: (3)(0)(4)(8)(CE)(M)(1) converts 3,048 metres into feet | |
| For areas: (1)(0)(0)(CE)(=)(7) coverts 100 sq, miles into sq. kilometres | |
| For volumes: (1)(0)(0)(0)(CE)(M)(-)(4) converts 1,000 cubic metres into cubic yards |
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The scan of the inside with the cover removed shows a remarkably low component count for such an early date. The batteries (removed) sit on the blue display ribbon cable connector. |
