This is the manual for a pocket Casio PB 100 computer from the 1980s.
Casio PB 100 Instruction Manual.
This machine still works today (2019) and it is generally a wonderful thing! This was a time when if you had a computer you were expected to do at least some programming - and most people who owned computers could therefore do some basic programming - that is just the way it was...
The companies and people who created the computer revolution minimized the amount of programming that users had to do themselves.