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Calculators: Handheld: Unitrex Executron 830
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Size (approx): |
80mm x 144mm x 20mm (w,h,d) Weight 118g excluding batteries. |
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Power: |
4.5V DC with 3 x AA size batteries. It accepts an adapter (DC420) through a socket on the top side to the right. The battery compartment has a black ribbon pull to aid battery removal. | ||
| Case: | Slab-shaped design in glossy and matt two piece plastic case. A neutral plastic display filter has a painted window and sits very slightly tilted in its own recess. Above this the on/off switch has embossed lettering. The black plastic keyboard surround is recessed with individual raised areas reminiscent of Commodore designs. The small keys are medium travel with a strong bounce back and soft click. A black printed metallic sticker sits in its own raised recess with the model name. | ||
| Display: | 8 digit blue VFD with a ninth digit for negative and error indicators. | ||
| Features: | Four function with percentages and change sign | ||
| Age: | 1975 | ||
| Manufacturer: | Made in Korea, Unitrex of Canada Ltd., Downsview, Ontario, Canada, serial number 5605376 | ||
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Comments:
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Rather plain design that looks a bit bottom heavy due to the battery compartment area being blank from the front. Striking resemblance to Commodore-type keys. The logic is not so good with negative zero bug and lack of any recovery. The original cover is soft black plastic with flip over top flap and front tuck-in section that looks big enough to accommodate a manual. Very similar to the Alco Alcor 888 and uses the same IC with different functions available. |
| Components: | 1 x cpu: Hitachi HD36290
5K41 (October 1975)
28 pin DIL , 0.6" width black plastic 1 x 9 digit VFD unit, single tube round face, Itron DP95K 2 x transistors 5 x diodes 6 x capacitors 22 x resistors 1 x transformer |
| Boards: | The main CPU board (832D-D ART 2-3-II 16290) sits loosely on top of the keyboard assembly (KB-6395-02 HM-20-12-RM6) which is fixed to the front with 7 screws. They are joined by 14 flying red wires. A cut out in the main board houses the transformer to keep the thickness down. |
| Construction: | Remove the battery compartment cover and then the four screws at the rear (two shorter ones inside the battery compartment). The back the lifts off easily, hinging to the left. |
| Logic comments: | The (CE) key is used to cancel number entry whilst (C) clears the whole calculator |
| Overflow on the input of a number is suppressed, keying in a ninth digit is ignored | |
| There is automatic constant on multiply and divide only | |
| Negative numbers are flagged by a "-" sign in the far left (ninth) digit thereby allowing full eight digit negative numbers. | |
| Overflow shows the result with a "C" (or "E" if negative) in the far left (ninth) digit and is not recoverable | |
| A divide by zero shows zero and "C" in the far left (ninth) digit and is not recoverable | |
| The change sign can be used in mid number entry but not before | |
| It suffers the negative zero bug: key in (1)(-)(2)(=) to give "-1" then (+)(1)(=) to give "-0" | |
| It almost suffers the divide to negative zero bug: key in (1)(-)(=) to give "-1" then (/)(1)(0)(=)(=)(=) etc. to eventually give "-0" then one more equals will give "0" showing the internal extra digit of precision |
