The german C64 magazine "64er" had an application which allowed "easy" entry of assembly applications by means of a hex encoding and used a checksum on each line to prevent bugs from typos. Still an incredible chore.
It was called "checksummer" which is a funny pun on check sum and "summer" which is the German word for buzzer. Oh, I should add that it made an annoying buzzer sound when you made a mistake.
