TI-57

The TI-57 is a discontinued product line of programmable calculators made by Texas Instruments between 1977 and 1982. There are three devices by this name made by TI. The first TI-57 devices with LED displays were released in September 1977 along the more powerful TI-58 and TI-59. The original devices have 50 program steps and eight memory registers. Two later versions named TI-57 LCD and TI-57 LCD-II have LCDs, but are less powerful (run much slower) and have much less memory: 48 bytes to be allocated between program 'steps' and storage registers. The TI-57 lacks non-volatile memory, so any programs entered are lost when the calculator is switched off or the battery runs out. The LED display version of the TI-57 was sold with a rechargeable nickel–cadmium battery pack BP7 containing two AA size batteries and electronics to raise the voltage to the 9V required by the calculator. A popular modification is to power it from a 9V battery and use the battery cover of a LED TI-30 or a part of the dismantled battery pack. This modification provides a better battery life than the original battery pack. Included, with at least the original version, was a book entitled Making Tracks Into Programming. It is subtitled "A step-by-step learning guide to the power, ease and fun of using your TI Programmable 57". Radio Shack also marketed this calculator, rebranded as the EC-4000.