The TI-55, known in Europe as the TI-51-III, is an early programmable scientific and financial calculator released by Texas Instruments in 1977.
 | |
| Other names | TI-51-III |
|---|---|
| Introduced | 1977 |
| Calculator | |
| Display type | Bubble LED |
| CPU | |
| Processor | TMC1503NL |
| Programming | |
| Programming language(s) | Keystroke |
| Interfaces | |
| Ports | DC power connector (on BP7 battery pack) |
| Other | |
| Power supply | 9V (stepped up from 2.4V supplied by internal battery pack), 5.7-8.6V external AC power supply |
| Power consumption | 120mW in power on state, 80mW in standby |
| Dimensions | 145(l) x 80(w) x 45(h)mm |
Features
Internal design
At the heart of the calculator is the Texas Instruments TMC1503NL calculator ASIC, which is the only integrated circuit in the calculator. Similar to other models in the Texas Instruments SR series, a metal dome based keypad is used, which provides noticeable tactile feedback when keys are pressed. As with many other pocket calculators of the era, the display uses bubble LED technology. The display has a 8 digit mantissa and two digits for exponents.
Battery power is provided by the Texas Instruments BP7 rechargeable battery pack. The BP7 contains two AA nickel-cadmium rechargeable cells, along with a board containing the the internal and external power connectors along with a DC-DC converter to boost the 2.4V output of the cells to 9V for use by the calculator. The external power connector accepts power supplies ranging from 5.7V to 8.6V AC. The internal power connector has two wires, red for negative and black for positive, inverted from the standard wiring colours.
Gallery
Internal design of the BP7 battery pack used in the TI-55
