Scientific RPN Calculator (with ATTINY85)

[deetee]

Thanks for these great compliments from one of the most honorable members of this forum and idol of every "calculator programmer".

Actually I am working on implementing and extending this code for an arduino (pro micro, 30k memory, 2k5 EEPROM, USB to PC) to get more features like programming - and to get closer to my favorite HP calculators (15c, 35s, WP34s).

Yes - I fought many weeks for every byte - and I am still searching for resources to eliminate bugs and implement more functions.

One thing to save memory is to use local variables. So I did with declaring the stack variables (xyzu) local. So I have to send to the push and pop subroutine the 4 variable pointers.
But I use this subroutine relative often - and did not check if it is worth to declare the stack as global variables. I will check.

Thanks again and regards
deetee