's name for the inverse
of the CHR$
, depending on dialect -- this was BASIC
!) function. ASC
would take a string (BASIC didn't have a character type!)
and return the ASCII
code of its first character
So ASC(CHR$(N)) was N, at least for <=N<255; CHR$(ASC(S$)) was the first character of S$.
I've no idea what ASC("") was. Probably 0, but maybe -1 or an error message. Most likely it varied between dialects; there was no standard for BASIC worth adhering to.