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Calculators: Handheld: Commodore 899A
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Size (approx): | 75mm
(max) x 147mm x 25mm (max) (w,h,d) Weight 110g excluding batteries. |
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Power: |
9.0V DC, 1 x PP3 size battery. Also accepts adapter (No. DC-620 or 505, 506 or 507) through a socket on the top side to the far left. | ||
| Case: | Cream coloured matt plastic two-piece case with matt black keyboard surround. Typical bright Commodore keys that are squishy but positive. A heavily sloping, convex red plastic display filter gives a good clean display though with limited angle of view. The Commodore logo is embossed in the top section of the front. | ||
| Display: | 8 digit red bubble-lens LED with a ninth digit for error, memory and negative signs. | ||
| Features: | Standard four functions, percentages, parentheses, reciprocal, squares, square roots, change sign, register exchange, pi and five function memory (including memory register exchange). | ||
| Age: | 1976-7 | ||
| Manufacturer: | Commodore made in England, serial number 128951 with another code on the rear sticker: Part No. 201413-03. | ||
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Comments:
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Wider body calculator to accommodate all the extra keys. Bold three-colour button system is more typical of Commodore compared to the very similar 899D. Solid logic with good recovery only let down by negative square roots. Absolute minimum of components inside to keep the costs down as prices dropped considerably around this time. |
| Components: | 1
x cpu: Commodore 3D32C ML980 CSP7644 (week 44 of 1976) 24 pin DIL 1 x 9 digit single unit bubble lens LED display |
| Boards: | The keyboard board (Ref 201 441 1 760 910 made in Japan) is fixed to the front using ten screws. This is attached to the main cpu board (Rev A 301502) via a 12-way ribbon cable. |
| Construction: | First remove the two screws at the back. 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 a ninth digit is ignored | |
| Negative numbers are shown with a "-" in the far left (ninth) digit thereby allowing full eight digit negative numbers | |
| Divide by zero shows zero and "E”" in the far left (ninth) digit and is recoverable using (C/CE) | |
| Overflow shows the result with "E" (negative or positive) in the far left (ninth) digit and is recoverable by using (C/CE) | |
| The change sign function can be used in mid number entry | |
| Negative square roots are allowed and result in a negative number | |
| Memory is indicated by the far left (ninth) digit showing an upper “n” | |
| (MT) is used to recall the total and clear the memory whilst (X-M) is used to exchange the memory with the current register | |
| Overflow in memory results in an error and stores the (shifted) result | |
| (X-Y) is used to exchange the current display with the register |
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