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Calculators: Handheld: Commodore Minuteman MM3MT
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Size (approx): | 75mm
(max) x 105mm x 27mm (max) (w,h,d) Weight 140g including batteries |
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Power: |
6.0V DC, internal rechargeable battery. 0.2A. Accepts adapter (undefined) through top end socket in the middle. This example still works today! Adapter should be 6V positive centre. | ||
| Case: | Lovely palm-sized white matt plastic calculator. Keyboard surround panel in black plastic and black painted metal display surround. The latter has a raised and silver painted logo and silver painted on/off label. Squishy but positive keys. Sticking with the red white and blue key colour scheme this compact calculator just oozes quality. | ||
| Display: | 8 digit LED with no lens, ninth digit for minus sign and error flags | ||
| Features: | Four function plus percentages and three function memory. | ||
| Age: | 1974 | ||
| Manufacturer: | Commodore Business Machines, Inc. Made in the USA. Serial No. 006487. | ||
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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. Inconvenient memory transfer function, switched constant and those dreaded "+=" type buttons are a pain, however. It sounds like the 3M bit of the model number represents a three function memory. Very similar to the Commodore MM3R. |
| Components: | 1 x cpu: Texas TMS0132NC 7409
(date code week 9 of 1974), 28 pin DIL, 0.6" width black plastic 2 x ICs: National Semiconductor DM75491N 415 display drivers, 14 pin DIL, 0.3" width black plastic 1 x nine digit red LED display 1 x transistor 4 x diodes 3 x resistors 4 x capacitors 1 x transformer 1 x GP Ni-Cd Battery pack P/N GP30AAK4BMU 4.8V 300mAh |
| Boards: | Main CPU board is is soldered to the keyboard board underneath. It has the reference numbers PCB 300531, ART 300532A, ASSY 300533 (with a box for a further mark). A 17 way ribbon connector joins to the display. |
| Construction: | Remove the two screws on the back and gently prize the calculator back away from the front. The battery floats but all the boards are attached to the front. |
| Logic comments: | (CE) cancels an incorrect numerical entry, pressing a second time (C) clears the calculator |
| An error results in the ninth digit showing "C" for overflow, "E" for negative overflow, "n" for memory overflow. Error status shows result but is not recoverable. | |
| Memory overflow hooks the calculator up until you press (MT) and view the result | |
| Minus sign is displayed in the ninth (far left) digit allowing full eight digit negative numbers. | |
| Input overflow is suppressed, typing in nine digits ignores the last one | |
| There is no memory flag - you have to remember it | |
| The (MT) memory transfer exchanges the memory contents to the current register and also deletes / replaces the memory amount which is rather annoying. | |
| It has switched constant on multiply and divide |
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