commodore p50

he is the p50 from 1977, the cheaper and cut down version of the pr100, its older and bigger brother. sporting 49 buttons, it looks impressive, but in reality it has no more functionality than most other scientific models, its just that features are not on shift keys.

it is programmable, but it has a rather limited 24 step capacity. despite 3 different conditional branches, you can't do much except evaluate simple formula. its also quite slow and even some of the manual operations (like factorial) have a noticeable delay.

it is powered by a pp3, 9v battery and inside there is only 1 chip and the display, making it cheaper to make. 

example program: nim, the matchstick game

here it is after only 27 years!, previously thought not possible: the matchstick game on a p50. fitting in 24 steps was considered not do-able, but here it is in only 20. the secret is the branchless logic, developed for the ti-51mk3. even though the p50 has branches using them makes the program too big.



enter a starting number greater than 1. this is the number of matches in the pile. each player takes turn to remove 1, 2 or 3 matches from the pile and the player taking the last match loses.

enter the start number (eg 10). the p50 plays first. press R/S. the number displayed (eg 9) is the pile size (so the p50 has taken 1). enter your play (eg 2) press '=' (shows 8 left), press R/S again and the p50 plays again to display 5 and so on. you can omit the '=' to play both your round followed by the p50's go.