Coding Blind: Programming the HP 48SX Without Manuals
Paper and pencil, literally. Computers weren’t available to me :). I eventually got 2nd hand HP 48SX calculator. No manuals. Spent week to figure out syntax/semantics of its programming language by trial and error. I wrote code without knowing the name of programming language :). https://x.com/davefarley77/status/1306262065829482497
Years later I learned that its language was called RPL, a LISP hybrid. I was using it very differently than “official” way :). I ended up writing ton of code, everything from assembler to video games. I was coding so much on it that I missed most of the classes and almost failed.
The person who sold me this calculator apparently had stolen from somewhere. He was selling cheaply because he was getting error even for 2+2 on that fency calculator. I bought it because only that fit in my budget and there was “programmable” label on it. No manuals though.
People get frustrated using 48SX calculator because everything gives error, including innocent 2+2. After days of struggle I found out 2 2 + worked. That was an insight that hit me like a lightning. Later I came to know about “reverse polish notation”. No internet in those days.
Once, in a programming competition, everyone had “real” PC but then power went out. So judges only had my 8085 assembler to judge, running on my calculator with 32KB memory, 2 MHz clock, 131x64 resolution display. I wrote it because I was tired of manual assembly in my class.
When I ran out of the built-in storage, I’d to delete some program because I’d no cables or flash cards. So I would laboriously write all code on paper and then enter it back one little key at a time for hours. One mistake and you have to find bug without debugger or IDE.