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Calculators: Handheld: Decimo Memory Man
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Size (approx): |
90mm
x 150mm x 31mm (max)
(w,h,d) |
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Power: |
6V DC, 4 x AA size batteries. It accepts an adapter (DC 6V, 200mA, 3.5mm plug centre positive) through socket on the top side to the far right. Quoted battery time is "6 hours at full digits displayed". The battery compartment has a ribbon pull to aid the removal of batteries. | |
| Case: | The two piece black smooth plastic case has rounded corners and bulging sides. It has two sets of grips either side of the display area. An oversized and slightly titled in green display filter gives an OK display with additional white printed numerals and the word "memory". The top section has a wrap-over brushed aluminium panel printed with the model name in black. There is a printed silver plastic sticker with the Decimo logo but this has slipped due to the soft adhesive. Bold colour scheme works well on the keys. They are long-travel squishy type with a soft metallic click with some needing a little extra pressure to work fully on my example. | |
| Display: | 8 digit green VFD, ninth digit for negative, memory and error indication | |
| Features: | Standard four functions, percentages, register exchange, change sign and five function memory | |
| Age: | 1975. My example came with the original receipt dated 12 July 1975 and it cost £28.00 + £2.80 value added tax from Wilding Bristol Office Equipment Ltd. | |
| Manufacturer: | Does not say who manufactured it; made in Japan, serial No. on the inside of the battery cover is 029702. | |
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Comments:
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Nearly too big and heavy to be classed as a hand-held but the finger grips were obviously meant to be held; it works well as a small desktop too. Built to last and it has. There is a very large plate on the back reminding you of the adapter specification and even a picture of the plug polarity. Sound logic with a strange underflow error state and trailing zero bug. The original case is soft black plastic with a leather effect pattern. It has a long flip over top with popper closing at the front. Early and expensive calculator. |
| Components: | 1 x cpu: cannot read,
panel topped 40 pin DIL, 0.6" width in its own socket 1 x nine digit single tube round faced VFD display 0 x transistors 4 x diodes 1 x capacitors 2 x resistor 1 x resistor array On the power board: 1 x transistor 4 x capacitors 5 x diodes 1 x resistor 1 x potentiometer 1 x transformer 1 x mini module with about six additional components |
| Boards: | There is a small power supply board mounted vertically in the top compartment above the display. The keyboard assembly (ref. 404264) sits on top of the main cpu board and is joined by a 14 way connecting block. It is also odd on one way it appears to be made easy to service: easy case opening, three board system and the IC socket. However, as the board-joining connecting block is soldered in it would be really difficult to separate. |
| Construction: | Remove the screw at the top and the front lifts off easily. |
| Logic comments: | (C/CE) key 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 sign is shown in the immediate left hand digit travelling into the far left (ninth) digit thereby allowing full eight digit negative numbers | |
| Divide by zero shows zero and "C" in the far left (ninth) digit and is recoverable using (C/CE) | |
| Overflow is shown by the result and "C" (or "E" if negative) in the far left (ninth) digit and is recoverable using (C/CE) | |
| The change sign can be used in mid-number entry | |
| Memory store is indicated by the upper horizontal segment of the far left (ninth) digit | |
| The (MT) key displays the memory contents and clears it. | |
| The percentage key just divides the current number by 100, continue to press it and eventually you will get an underflow error; it displays the last result with a reverse "C" and is recoverable using (C/CE) | |
| There is some strange behaviour with trailing zeros. Try (9)(/)(1)(0)(=) and keep pressing equals. Eventually you will have a display that reads "0.0000000" which is you add one (+)(1) will keep the trailing zeros. You can actually use this feature to set a fixed decimal point calculation. For four digit calculations key in "0.0000" then add your first number. The calculator will now stay in four digit mode until cancelled by a multiply or divide. This is not mentioned in the manual so I assume it is a bug. |
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The oversized box above measures 220mm x 135mm
and is 55mm deep. From this orientation, the front hinges off from the
top exposing a large polystyrene former which houses the calculator in its
cover and what looks like space for batteries.
There is no branding or mention of origination but there is a sticker on the side with a matching serial number. Obviously a no-name, no-design box for a generic model. |
The manual above measures 151mm x 104mm
and has a full colour cover with black only internal pages. Totalling
eight pages it has a good description, plenty of examples and a nice picture
of the calculator. No origination information.
Notice that the calculator shown has no brand name, no brand badge and no printing on the aluminium panel. It was obviously designed to be a generic calculator, branded at the last minute.
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