Híradástechnika TK-891
Brief History
The first scientific model (TK-835) was a success in 1974, but the bankruptcy of the canadian partner made the whole production impossible.
A new supplier was found: General Instrument Corporation, which manufactures calculator chips and in this time, complete calculators too.
A new four-function basic calculator was planned and built from parts (K-841), and the EZ-3500 scientific model (TK-891) were started to
assemble at Balatonlelle factory in 1975. Inaccuracy, insufficient capacity and lack of some widely used functions made this calculator unpopular.
In the next year the TK-1023 was introduced.
| Manufacturer: | Híradástechnika Szövetkezet (Hungary) |
| OEM: | General Instrument of Canada Ltd. (Canada) |
| OEM model: | EZ3500 |
| Mfg. date: | 1975 |
| Size: | 7,7×15,2×2,5 cm |
| Weight (ready for operate): | 152 g |
| Type: | scientific |
| Capacity: | 8/5+2 digits (input/display) 8/8+2 digits (internal precision) |
| Operating logic: | algebraic |
| CPU: | General Instruments CF596 |
| Registers: | 2 standard (with saving the pending operation) 1 constant (with saving the pending operation) 1 memory (with aritmetic) |
| Features: | Ffloating-point notation Sciscientific (exponential) notation Sqrsquare root pivalue of pi (3.1415..) can be recalled 1/xreciprocal trigtrigonometrical functions (sin, cos, tan and inverses: arcsin, arccos, arctan) logexponential and logarithmical functions (10- and e-base) |
| Display: | 9 digit LED (Bowmar Optostic) |
| Power: | 9V battery E-05D adaptor |
| Test results: | trigonometry:result of sin-1(cos-1(tan-1(tan(cos(sin(60°)))))), reference value: 60. 67.497 exponential:result of 0.999160000, reference value (first 14 digits): 3.0068804206375×10-70 - |
TK-891
Inside of the TK-891
TK-891 with original packaging
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