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Size (approx): |
73mm
x 120mm x 19mm
(w,h,d) |
| Power: | 6V DC, 4 x AAA size batteries. It does not accept an adapter. | ||
| Case: | Square case with back and sides made of a U-shaped piece of brushed aluminium. Black plastic calculator body slides down nearly half way to reveal battery compartment. Pronounced ridges on the side to aid grip. Squishy but positive action keys in a variety of colours and silver printed functions. The brand and model number is printed on an inset aluminium panel. Logo is also painted on the top side in white. The green, inst and sloping plastic display filter gives a clean bright image. | ||
| Display: | 8 digit green VFD with a ninth digit for negative, error and function indicators | ||
| Features: | 4 function calculator with change sign, pi, square root, register exchange, reciprocal, trigs, logs, powers, DR function and four function memory. Switched degrees / radians mode. | ||
| Age: | 1975 | ||
| Manufacturer: | Manufacturer: TA Vertriebs GmbH, D8500 Nurnberg, Germany. Type EC 25, Serial No. 68.627.441 | ||
| Comments: | Unusual slide out design clear display and weighty quality-feeling calculator. Button colours are a bit of a jumble. The logic is not too bad for a 1974 IC with good recovery and really only let down by the inaccuracy of powers and pseudo fixed decimal bug. The cover is black stiffened plastic with collapsible edges, open top and large square side cut-outs. |
| Components: | 1 x cpu: Rockwell A4001 15471PC
7451 (week 51 of 1974), 42 pin staggered DIL, 0.6" width ceramic with
metal cap 1 x 9 digit VFD flat face single tube display: Futaba 9-ST-12 4L (November 1974) 2 x transistors 4 x diodes 6 x capacitors 2 x resistor arrays 6 x resistors 1 x transformer: Zebra DCT-04 |
| Boards: | The keyboard assembly (GICO GK135-511) (GICO 49.12.10 - date code 10th December 1974) sits on top of the battery compartment and main cpu (88TD-1) board. They are joined by 16 strong short wires. The whole assembly sits loose, held in place by the battery terminal connections. |
| Construction: | Push the sides down as if to change the batteries. Whilst gently pulling out the metal sides, continue to pull the body of the calculator down through the metal stops. Remove the two screws on the sides and the front will lift away easily. |
| Logic comments: | The (C) key is used to clear last entry of a number and a second time to clear the whole calculator |
| Overflow on number input is suppressed: keying in a ninth digit is ignored | |
| There is automatic constant on all four functions | |
| Negative numbers are flagged by a "-" sign in the far left ( ninth) digit thereby allowing full eight digit negative numbers. | |
| Overflow shows the result shifted and "n" in the far left (ninth) digit and is recoverable using (C) | |
| An function overflow error displays zero and an upper "n" in the far left (ninth) digit and is not recoverable | |
| Divide by zero shows zero and an upper "n" in the far left (ninth) digit and is recoverable using (C) | |
| The change sign (-) function can be used in mid number entry and before | |
| The (X<>Y) key is used to exchange the current display for the last register whilst the (X<>M) key exchanges the memory contents | |
| Memory store is not indicated - you have to remember it though I know that this IC supports a memory flag | |
| Negative square roots are not allowed and result in zero and "n" in the far left (ninth) digit and is not recoverable | |
| Higher functions are selected by pressing the (F) key first, which causes the decimal point of the far left (ninth) digit to light up. It is cancelled by pressing the (F) key again. | |
| The power key is quite inaccurate and you can see the intermediate logarithm algorithm used: key in (2)(Xy) [where the log of 2 is displayed] then (8)(=) to give "255.9995" rather than 256. You can get the same result by (2)(F)(lnx)(X)(8)(=)(F)(ex) | |
| A switch allows you to chose between degrees and radians | |
| The (DR) key does not work on my example. Most web sites infer this is a degree radian conversion key, but I suspect it is a chain calculation correct key. | |
| It suffers the pseudo fixed decimal bug: key in (1)(+)(.)(0)(0)(0)(=) to give "1.000" which remains a fixed three digit decimal number until you need more or use a higher function |
