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Calculators: Handheld: Commodore 7923
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Size (approx):
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67mm
(max) x 157mm x 25mm (max) (w,h,d) Weight 84g excluding batteries. |
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Power:
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9.0V DC, 1 x PP3 size battery. It accepts adapter (DC-620R or 505, 506, 507) through a socket on the left hand side in line with the word Commodore. |
| Case: | Beige matt plastic two-piece case with brushed aluminium keyboard surround. Not so typical squishy-click oblong keys that work well enough. A heavily sloping, flat red plastic display filter gives a good clean display though rather limited in viewing angle. Silver painted raised logos have survived rather well. The key labelling is reversed out printing in black and has also survived remarkably well. |
| Display: | 8 digit red bubble-lens LED with a ninth digit for error, memory and negative signs. |
| Features: | Standard four functions with register exchange, percentages and four function memory |
| Age: | 1978 |
| Manufacturer: | Commodore, serial number 51132. Label part No. 201444-04 made in Hong Kong. |
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Comments:
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This tall slim shape was used for many late Commodore calculators - primarily to cope with the bulk of the battery at the top. Metal keyboard surround was the rarer configuration in the later years - and I presume was cheaper to make. Solid logic for this grade of calculator, except for the lack of overflow recovery. Probably the last line of calculators that Commodore made. |
| Components: | 1 x
cpu: MOS MPS 7564 102 0778 (week 07 of 1978) 24 pin DIL, 0.6" width 1 x 9 digit single unit bubble lens LED display 1 x diode (obviously an afterthought as it is soldered to the display pins) |
| Boards: | The keyboard board (Ref: GICO 53.1.24 0-8) ( Date code 1978 January 24) is secured to the front via 12 plastic rivets and four side lugs. It connects to the floating cpu board (Ref: 201011 Rev B TW-17 Japan) via a 14-way ribbon cable. |
| 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: | (C/CE) is used once to cancel the last number entered and a second time to clear the whole calculator. |
| There is automatic constant on all four functions | |
| Input overflow is suppressed, inputting an ninth digit is ignored | |
| Negative numbers are shown with a "-" in the immediate left hand digit travelling into the ninth to allow eight digit negative numbers. | |
| The (MR) key recalls the memory, the (MT) key totals the memory and clears it | |
| Memory store is indicated by the ninth (far left) decimal point | |
| Divide by zero shows "E" in the far left (ninth) digit and is not recoverable. | |
| Overflow shows the result with "E" (negative or positive) in the left (ninth) digit and is not recoverable | |
| You can store an overflow in memory which does not flag until you recall it | |
| (EX) is used to exchange the display with the last register | |
| The (%) button divides by 100 |
