Environments vary substantially between computers, so you’ll often see environment-specific code hidden in the PEEKs and POKEs of old BASIC programs.
We’ll take a brief tour of the Ohio Scientific and Commodore 64, two computers from the late 1970s to early 1980s.This article will give pointers to supporting material, so we can still glean lessons from the old software.
The OSI machines were fairly popular for their time. The Model 500 came out in 1977, but by 1982 OSI had been sold, shifted focus, and changed its name.
Notice that the letters and symbols have a blank rightmost column and bottom-most row. There’s no kerning control on these:)
There is a BASIC routine that typically runs, which looks for ^C (as a break key) while you’re running. You turn this off by POKE 530, 1, and turn it back on with POKE 530, 0.
Just to keep things fun, some models use positive logic – set the flag corresponding to the rows/columns you want to use; others use negative logic – set the flag for the rows/columns you don’t want to use.