Up to 79 characters, including the line number. Interestingly, this was basically (ha) an editor limitation, not a language one. You could use 2-letter abbrev

Up to 79 characters, including the line number. Interestingly, this was basically (ha) an editor limitation, not a language one. You could use 2-letter abbreviations for the language's reserved words to cram more code into the same space. The programs were stored (IIRC) in tokenized form.