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Calculators: Handheld: Unknown CO 12 X
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| Size (approx): |
83mm
(max) x 132mm x 30mm (max) (w,h,d) Weight 144g excluding batteries |
| Power: | 6.0V DC, 4 x AA size batteries. It accepts an adapter (undefined) through a top side socket on the right. The on/off switch is in the middle of the top side. |
| Case: | Chunky two piece matt plastic case where the bottom is black and the top white. Unusual small green display filter has a silver printed escutcheon. This does not work well and you can easily see the inner plastic lugs and mounts. A black printed metallic sticker with the model number sits in its own recess. The keyboard surround is black matt plastic. The top is slightly tilted upwards, including the back which causes the calculator to rock, especially with no batteries to weigh it down. Keys are squishy but positive to use. |
| Display: | 6 digit green VFD display with a seventh symbol cluster for negative and overflow indicators. Display is left leading rather than modern right reading standard. |
| Features: | Basic four function with display shift |
| Age: | 1974 |
| Manufacturer: | Unknown, made in Japan, serial No. 001865 |
| Comments: | Unusual Decimo Vatman-type calculator with the case colours inverted and a small window display filter rather than a wrap around one. The logic is OK with true 12 digit calculation possible but the lack of recovery and negative zero bugs let it down. Appears to be similar design to Decimo calculators but I do not know of a model with the same functions. If anyone has any information on this calculator it would be a great help. |
| Components: | 1 x cpu; Matsushita (three leaf
design) MA8168P 2429, 24 pin DIL, 0.6" width black plastic 1 x 6 digit plus symbol cluster VFD; single round faced tube 1 x transistor 8 x diodes 6 x capacitors 3+ x resistors 1 x resistor arrays 1 x transformer |
| Boards: | The keyboard assembly (GICO Japan 49.2.15) (date code 15 February 1974) sits on top of the battery compartment and is attached to the main cpu board (120K-B) below with a 9 strong wires. The main board has a piggy-back assembly for display driver power. |
| Construction: | Front can be gently prized off after using the coin guide at the top. Squeeze the rear plastic sides so the lugs separate without breaking. |
| Logic comments: | The Clear key (CE) is used to clear an input number whilst (C) resets the calculator |
| You can enter up to 12 digits but after the sixth a right pointing arrow lights to tell you there are least significant digits. Press the (<->) key to briefly view these digits | |
| Overflow on the input of a number is suppressed - typing in a thirteenth digit is ignored | |
| There is automatic constant on all four functions | |
| The negative sign is shown by a "-" in the far left symbol cluster digit thereby allowing full twelve digit negative numbers. | |
| A divide by zero shows "->......" and is not recoverable | |
| Overflow shows "->......" and is not recoverable | |
| The calculator suffers the negative zero bug; key in (1)(-)(2)(=) to give "-1" then key in (+)(1)(=) to give "-0" | |
| It also suffers the divide to negative zero bug: key in (-)(1)(=)(/)(1)(0)(=)(=)(=) etc until you eventually get "-0." |
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Exactly the same
basic construction as many Decimo calculators. Here you can easily
see the components crammed into the top of the case - the whole of the
bottom being taken up by the keyboard assembly on top of the battery
compartment.
The main CPU is just showing on the right hand side and you can just make out the arrow/minus symbol cluster on the left-most digit of the display tube. |
