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Calculators: Handheld: Commodore GL-997R
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Size (approx): | 75mm x
140mm x 28mm(max) (w,h,d) Weight 172g including batteries, 122g without. |
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Power: |
Undefined voltage but works on 3V DC, two internal, AA size rechargeable batteries. Does accept an adapter/charger (996R & 997R, 2mm plug, centre positive) through socket on the right side just above midway. | ||
| Case: | Three piece sturdy case in black and white matt plastic. The top front has an oversized green plastic display filter that is flush with the case an has a sloping inset section. It gives a bright image and it has the Commodore logo raised and painted silver along with the words "Custom Green Line". Bold red, white and blue keys have their own raised surrounds. They keys are wobbly and squishy but work well enough. Below the keyboard is a black printed metallic sticker with the company name, which sits in its own recess. | ||
| Display: | 8 digit green VFD, with a ninth digit for memory indication, minus and error signs. | ||
| Features: | Standard four functions, percentages, register exchange, and four function memory. | ||
| Age: | 1975 | ||
| Manufacturer: | Commodore Business Machines, made in the UK, serial No. 55738. | ||
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Comments:
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Typical member of the Custom Green Line series. This example shows well that the original light plastic case was white, often they are yellowed with age to a cream colour. The original rechargeable batteries still work, so the build quality must have been good. Solid logic but odd memory cancel system. Original case is an unusual tan coloured mottled plastic with flip-over top and popper closing. |
| Components: | 1 x cpu: Commodore GRBP-89 7531
(week 31 of 1975) 24 pin DIL 1 x 9 digit single round tube VFD display 2 x transistors 4 x diodes 5 x capacitors 2 x SIL resistor arrays 5 x resistors 1 x transformer |
| Boards: | The keyboard board (Ref: KB-6237-12 HM-24-10-RCB is fixed to the front with 11 screws and has numerous link wires. It is connected to the main cpu board (Ref: PCB200432 ART-200433 Rev-A) with a 14-way ribbon cable |
| Construction: | Remove the two screws from the back of the case. Gently squeeze the cream plastic sides and the back will separate eventually. You have to loosen the adapter socket to lift the main cpu board. |
| Logic comments: | (C) 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 a ninth digit is ignored | |
| Negative numbers are shown with a "-" in the far left (ninth) digit allowing eight-digit negative numbers | |
| The (MT) key transfer the contents of the memory to the display register and cancels the memory contents | |
| Memory store is indicated by the decimal point in the far left (ninth) digit. | |
| Divide by zero shows "E00000000" (no decimal point) and is recoverable by division by 1 | |
| Overflow shows the result with "E" (negative or positive) in the left most (ninth) digit and is recoverable by continual division by 10 or a multiple | |
| (EX) is used to exchange the display with the last stored initial number. i.e. (5)(X)(6)(=) result in "30". Pressing (EX) recovers the "5". | |
| The (%) button divides by 100 so can be used to recover from overflows |
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The scan on the left shows a typical early green line layout. The majority of components along the top are the voltage doubling circuitry for the VF display. |
