casio fx-502p

it has 256 steps of merged keystroke, non-volatile program memory distributed over 10 program slots, p0 thru' p9. 22 memories, labels, conditional branches, subroutines (4 levels), increment/decrement loops and indirect memory and jump addressing and one of the first machines to offer a 10+2 display. ten levels of brackets were also more than most. memory wise, everything was double the fx-501p, including program store, registers and brackets. although the 501p was not released earlier, it was positioned as a cut down version.

compared to the hp41c, a competitor at the time, it was cheaper, could not be expanded and had no alpha capability. on the plus side, it was cheaper to acquire the fa-1 adapter for tape based storage than the equivalent hp41c offering. it was also slimmer and more pocket sized.

to edit programs, you had a plastic overlay which showed the row/column keycode. this you had to use to decipher the program steps, until you learnt them by heart, that is. another keyboard overlay was supplied with musical notes printed. this was used to program the music feature. basically, the music feature was a bonus derived from the fact that the values in the program steps could be made to play notes through the fa-1 interface.

the lack of alpha would be seen as a major drawback today, but at the time, alpha capability was unheard of except on the hp41c. other features missing now more standard include, number bases, 2d stats (it has only 1d stats) and memory partitioning. casio followed up this model with the fx-602p which did have an alpha numeric display, more memory and partitioning.

the machine came with a comprehensive program library whose programs were originally derived from the fx-201p program library and later turned into the fx-700p library. it seemed that casio were fond of their programs, only adding new ones to exploit the unique features of new models.

the unit is powered by 2 G13 button cells.

recently i found some cool stuff that i never knew the 502 could do, here,