ti 57

the ti57 appeared in 1977 and was the least sophisticated of the 57,58 & 59 range but more competent than the earlier ti-51-iii (ti-55). it is programmable with a 50 step volatile memory.

the program steps are fully merged keystrokes, which is good because several common operations require three key presses (eg INV 2nd x==t). it has all the expected program features, subroutines, labels, conditional branches and decrement loops (dsz).

50 steps wasnt a lot, but the versatility of conditionals and especially the `t' register meant that useful programs could be written. moreover, the machine was affordable in comparison to the much more expensive ti-58 and ti-59 models.