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Calculators: Handheld: Conic LED 650
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| Size (approx): |
72mm x
132mm x 18-25mm (w,h,d) |
| Power: | 9V DC using 1 x PP3 size battery. It accepts an adapter (DC 9V 2.5mm plug centre negative) through a socket on the right side in line with the brand. The on/off switch is on the left hand side in line with the first row of keys. |
| Case: | The calculator is made from a two-piece matt black plastic case which is sloped at two different angles, making it almost wedge shaped. The front is dominated by a gold coloured metal plate with brushed-effect finish. It is printed with black text for the brand and model number, key labels and grid design around the keys. The red display filter is flush and tilted to give a good if limited angle of view image. They keys are short travel loud click type but feel cheap. |
| Display: | 8 digit red LED with individual bubble lens and no ninth digit |
| Features: | Standard four functions with change sign, percentages and four-function memory |
| Age: | 1979 |
| Manufacturer: | No information on origin, serial number 61101268 (though I suspect this is made in Hong Kong). |
| Comments: | Cheap, lightweight calculator from the height of the price discounting era. Similar in feel to the blue and white Texet models with a single chip , display unit and nothing else. I believe there was also a model 750 with no memory. Very similar to the Scientec XS-5297. |
| Components: | 1 x cpu; Texas
TMS0972NL NBT 7901 (week 01 of 1979), 28
pin DIL, 0.6" width 1 x 8 digit red LED display unit with individual bubble lens 0 x transistor 0 x diodes 0 x capacitors 0 x resistors 0 x transformer |
| Boards: | The main cpu board (fi Rev A. PCB 186010) sits clipped onto the front of the calculator and is joined to the main keyboard assembly via a 14-way connector which on my example has every single wire broken! |
| Construction: | Very difficult to open as this case is held together with internal lugs - I do not recommend trying to open it for fear of damage. The easiest way I found was (after removing the screw on the back) to use a finger nail to prize out and push out the rear section along the top side. Eventually the rear section will lift off. |
| Logic comments: | (CE) clears the last number entered whilst (C) clears the whole calculator |
| Input overflow is suppressed, keying a ninth digit is ignored | |
| There is automatic constant on all four functions | |
| 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 | |
| Overflow shows the result flashing which is recoverable using (CE) | |
| Divide by zero shows "0." flashing which is recoverable using (CE) | |
| The change sign function can be used in mid number entry and before | |
| There is no indication of memory store - you have to remember it | |
| Overflow in memory hooks up the calculator and is not recoverable and you lose the memory contents | |
| The percentage key used in isolation will cause a divide by zero error | |
| It suffers the pseudo fixed decimal bug: key in (1)(+)(.)(0)(0)(0)(=) gives "1.000" which remains a fixed three digit decimal number until you need more digits or use multiply or divide |
