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Calculators: Handheld: Commodore 797M
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Size (approx): | 64mm
(max) x 135mm x 25mm (max) (w,h,d) Weight 74g excluding batteries |
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Power: |
9V DC, 1xPP3 size battery. Also accepts adapters DC-505, 707, 708 or 709 through left side socket in the middle. | |
| Case: | Typical middle-bulge, wedge shaped Commodore shape for this two-piece, beige plastic case. The logo and company name is in raised letters painted silver, which have survived well on this clean example. However, away go the bold primary-coloured buttons, and in comes a brushed aluminium keyboard surround and black painted letters, The flat red plastic display filter is heavily inset and gives a bright image but with a limited angle of view. The keys are very springy with a positive stop. | |
| Display: | 8 digit red LED with bubble lens with a ninth digit for negative, error and memory indicators | |
| Features: | Standard four function with percentages, register exchange and four-function memory. | |
| Age: | 1979 | |
| Manufacturer: | Commodore Electronic Calculators. Made in Hong Kong. Serial No. 059436. Rear sticker part no. 201092-05. | |
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Comments:
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Tall and thin design which was obviously cheaper to make than the earlier Commodore models. Keys are a bit squishy, and a little too close, you can feel the adjacent buttons when you press one. Interesting that they kept the EX function, as this was usually to help with the lack of a memory. However, the logic is very sound with good recovery. One of the last Commodore calculators made cheaply and sold cheaply. |
| Components: | 1 x
cpu: MOS MPS 7560 3079 (week 30 of 1979) 22 pin DIL, 0.6" width 1 x 9 digit single unit bubble lens LED display |
| Boards: | The keyboard board is also the cpu board and sits in the body held by four plastic lugs (Ref: GICO 54.7.21 0-17) ( Date code 1979 July 17). |
| Construction: | Remove the single screw from within the battery compartment. Then, from the rear, use a small screwdriver to push the lugs to the outside in the lower lug recesses. The back then lifts off by hinging off the two small top lugs. |
| Logic comments: | The (C/CE) button is used once to clear entry of a number, a second time to clear the calculator |
| Overflow on number input is suppressed | |
| Overflow is flagged by the result and "E" in the far left (ninth) digit and is recoverable by repetitive division by 10 or a multiple. | |
| Divide by zero shows "E00000000" and is recoverable by dividing by one | |
| It is possible to store an error in the memory. This results in memory recall (MR) being an error! | |
| Negative numbers are flagged by a "-" sign in the far left (ninth) digit, allowing full eight digit negative numbers. | |
| The (EX) key exchanges the last entered number with the previous register | |
| The (MT) key recalls the memory and clears it |
