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Calculators: Handheld: Casio Pocket-mini (aka P-811)
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|
Size (approx): |
63mm
x 106mm x 21mm (w x h x d) |
| Power: | 3.0V DC using 2 x AA size batteries. It accepts an adapter (0.2W, AD-2S) through a socket on the right side at the bottom. The on/off switch is located on the left side in line with the Casio logo. | |
| Case: | The case is two-piece smooth white and black plastic and is very compact with rounded edges and corners. An oversized neutral display filter is flush and slightly raised and has white printed text with the make and model number. Whilst my example has a rather dim display it is clear and easy to read. They keys are short travel, squishy type typical of Casio with a brushed aluminium surround and individual key escutcheons. | |
| Display: |
8
digit blue VFD with no ninth digit |
|
| Features: | Standard four functions with percentages and one-function memory. | |
| Age: | 1976 | |
| Manufacturer: | Casio Computer Company Ltd, made in Japan. Serial number 0628797 is on a sticker inside of the battery compartment. | |
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Comments:
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A typical Casio which is about as compact as you could get; it is only just wider than an AA battery. Basic functions and poor logic with no ninth digit, “negative zero” bug, basic memory and lack of recovery. The Pocket-mini name was used for a number of calculators so you need to use the extra reference number. |
| Components: | 1 x cpu; Hitachi HD3691A 6C43
(March 1976), 28 pin DIL, 0.6" width 1 x 8 digit VFD display; single tube round faced, NEC LD8128 2 x transistors 5 x diodes 12 x capacitors 5 x resistors 2 x resistor array 1 x transformer |
| Boards: | The main cpu board (C8D-1A) sits loosely above the keyboard assembly (C8D-E4B) and is joined by 13 strong copper wires. The latter is attached to the front with four screws. There is a small piggy-back board with the transformer and display voltage generator circuit. |
| Construction: | Remove the two screws from inside the battery compartment. Gently lever out the top and sides of the white rear section to pop the two lower side lugs. The back then lifts off easily, hinging around the adapter socket. |
| Logic comments: | The (C) key is used to cancel an entry whilst the (AC) key clears the whole calculator |
| Input overflow is suppressed inputting an ninth digit is ignored | |
| Negative numbers are shown with a "-” in the immediate left digit but as there is no ninth digit to travel into you are limited to seven digit negative numbers. | |
| There is automatic constant on multiply and divide only | |
| Divide by zero just shows “E.” in the far right (first) digit and is not recoverable | |
| Overflow just shows “E.” in the far right (first) digit and is not recoverable | |
| Memory store is automatically accumulated every time you hit the (=) key. The (AC) key clear the contents and the (MR) key recalls it. | |
| There is no indication of memory store you have to remember it | |
| This calculator has the “negative zero” bug; try (1)(-)(2)(=) to give “-1” now (+)(1)(=) will give you “-0”. |
