In the Fixedsys typeface, the numeral 0 has two internal barbs along the lines of the slash, which can alternately be considered a narrow “S” within the zero.
•
The use of the slashed zero by many computer systems of the 1970s and 1980s inspired the 1980s space rock band Underground Zerø to use the Scandinavian vowel ø in the band's name and as the band Logo on all their album covers (see link below)
An alternative, the slashed zero (looking similar to the letter O except for the slash), was primarily used in hand-written coding sheets before transcription to punched cards or tape, and is also used in old-style ASCII graphic sets descended from the default typewheel on the Teletype Model 33 ASR.