TI-57
The TI-57 was a programmable calculator made by Texas Instruments between 1977 and 1982. There were three machines by this name made by TI, the first was the TI-57 with LED display released in September 1977 along the more powerful TI-58 and TI-59. It had 50 program steps and 8 memory registers. Two later versions named TI-57 LCD and TI-57 LCD-II have a LCD display, but were less powerful and had much less memory: 48 bytes to be allocated between program 'steps' and storage registers.
The TI-57 lacked non-volatile memory, so any programs entered were lost when the calculator was switched off or the battery ran out.
The LED display version of the TI-57 had a rechargeable Nickel-Cadmium battery pack BP7 which contains 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 was self described as "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.
Programming
The programming capabilities of the TI-57 were similar to a primitive macro assembler.Any keystroke could be stored, along with some simple program flow control commands and conditional tests. These included:
GTO : Causes program pointer to jump immediately to a Label or to a specific program step.
SBR : Causes a program to jump to a Label, and on encountering an Inv SBR command, continue executing at the instruction immediately following the original SBR.
DSZ : Decrements storage register zero, and skips the next instruction if the result is zero. There was also an inverse form, Decrement and Skip if Not Zero.
Tests for equality/inequality could be performed against a value on the display and a dedicated test register, t. The result of the test would cause the next instruction to be conditionally skipped.
Programs could be edited by inserting, deleting, or overwriting a program step.
A NOP function was provided to allow a program step to be ignored.
Due to the hard limit of 50 program steps, use of NOP was infrequent.
The TI-57 used the "one step, one instruction" principle, regardless of whether one instruction required one or up to four keypresses.
Sample program
The following program generates pseudo-random numbers within the range of 1 to 6.| Step | Code | Key | Function | Comment |
| 00 | 30 | π | Pi | |
| 01 | 75 | + | ||
| 02 | 33 0 | RCL 0 | Recall register 0 | |
| 03 | 85 | = | ||
| 04 | 35 | yx | ||
| 05 | 08 | 8 | ||
| 06 | 65 | − | ||
| 07 | 49 | Int | Integer function | |
| 08 | 85 | = | ||
| 09 | 32 0 | STO 0 | Store result in register 0 | |
| 10 | 55 | x | ||
| 11 | 06 | 6 | Upper bound of the random number | |
| 12 | 75 | + | ||
| 13 | 01 | 1 | ||
| 14 | 85 | = | ||
| 15 | 49 | Int | Integer function | |
| 16 | 81 | R/S | Stop | |
| 17 | 71 | RST | Reset |