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Calculators: Handheld: Texas Instruments TI-2550 Memory Calculator
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Size (approx): |
80mm
(max) x 164mm x 45mm (max) (w,h,d) |
| Power: | 6.0V DC, 4 x AA size batteries or 3 x AA-size rechargeable batteries. Also accepts adapter/charger (AC9130) through a top side socket on the left. Rechargeable pack gives 4 to 6 hours continuous use. | |
| Case: | Off-white sturdy matt finish plastic case with black facia (matt) and keyboard surround (smooth). Considerably titled up at the back and contains a inset red plastic display filter which makes viewing very good. Battery compartment has rotary lock turned with a coin. On/off switch on front at the far top right corner. | |
| Display: | 8 digit red LED display - ninth used for minus, error and memory signs. | |
| Features: | Basic four function with percentages and four function memory. Switch for floating, two or four decimal points. | |
| Age: | 1974 | |
| Manufacturer: | Made by Texas Instruments Incorporated. Dallas Texas. Serial No. 2550416263 | |
| Comments: | Solid feeling calculator with very nice wide angle LED display that does not use bubble lenses. Logic quite robust. Decimal point switch just like the old days! However, it's very ugly. |
| Components: | 1 x cpu Texas
TMC060INC D7505 (week 5 1975?) 2 x 7422 logic gates 1 x 7410 logic gate 1 x SN75494N logic chip 1 x smoothing choke 20 x resistors 16 x diodes 5 x transistors 7 x capacitors 1 x 9 digit flat panel LED display |
| Boards: | Main board (1030582 Assy 1030583) is held down by two screws and joined to the keyboard board (Texas Instruments Rev D IKS 146 45330) by 13 strong wires. |
| Construction: | Opened by undoing three screws in the base. |
| Logic comments: | The Clear Entry key (CE) is used to clear an input number, the Clear (C) to completely reset the calculator |
| Overflow on the input of a number is suppressed | |
| The constant function is automatic for all operators | |
| The negative sign is shown on ninth digit to allow 8-digit negative numbers | |
| An overflow or divide by zero error is shown by an "L" in the ninth digit and is not recoverable | |
| Memory storage is indicated by an "r" in the ninth digit |
