At least as early as 1977 the Commodore PET and the Apple ][ had "slashed zeros"; followed by the Atari 400/800 in 1979, the BBC Micro in 1981 and the Sinclair

At least as early as 1977 the Commodore PET and the Apple ][ had "slashed zeros"; followed by the Atari 400/800 in 1979, the BBC Micro in 1981 and the Sinclair ZX Spectrum and Commodore 64 in 1982: https://damieng.com/blog/2011/02/20/typography-in-8-bits-system-fonts https://damieng.com/blog/2011/02/20/typography-in-8-bits-sys... Uh, ok. Turns out it was the 12th and 13th century that it was first known to have been used! https://en.wikipedia.org/wiki/Slashed_zero#Origins https://en.wikipedia.org/wiki/Slashed_zero#Origins