There's some subjectivity in where you consider it standardized, but I would put it later than that. Throughout the period when IBM's System/360 was popular, DE

There's some subjectivity in where you consider it standardized, but I would put it later than that. Throughout the period when IBM's System/360 was popular, DEC's PDP series was also popular, which used 36-bit words and a somewhat varying definition of what constituted a byte. If I had to pick a date, I'd pick 1977 as when it solidified. A few elements: ARPAnet standardized on octet-based protocols in the early 1970s, and was getting widespread by the mid 1970s; three popular microcomputers based on 8-bit architectures were introduced in 1977 (the Apple II, TRS-80, and Commodore PET); and DEC introduced the 32-bit VAX in 1977.