That's a tough question. The slash-0 (for decimal zero) had been in use long before the BASIC and the ASR-33 came along. (In ham radio for one.) Dartmouth or Te

That's a tough question. The slash-0 (for decimal zero) had been in use long before the BASIC and the ASR-33 came along. (In ham radio for one.) Dartmouth or Teletype may have had a reason for trying this ... but it didn't last! [Edit] OK, think I found the culprit. "The rule which has the letter O with a slash and the zero without was used at IBM and a few other early mainframe makers; this is even more of a problem for Scandinavians, because it looks like two of their letters at the same time." -- https://simple.wikipedia.org/wiki/Zero#Telling_zero_and_the_letter_O_apart https://simple.wikipedia.org/wiki/Zero#Telling_zero_and_the_...