My god, look at this absolutely lovely* Venn diagram showing the overlap (and non-overlap) of characters supported by various popular computing systems in 1972. Notably, the ¢ symbol is supported in IBM's EBCDIC but not in anything else. (ASCII here means what we now think of as 7-bit ASCII, only the first 128 ASCII codes. 256-character ASCII wouldn't be formally standardized until 1987 in ISO 8859!)

RFC 338 (PDF):

*lovely... but maddening

@darius odd that the asr33/35 character set included [ and ]. Those keys aren't present on the teletype that I restored.

@darius although perhaps alternate type wheels had those characters.

Curiousmarc is doing a set of restoration videos of the ASR-33 and I'm pretty sure that I saw those symbols its keyboard

@darius at&t out here with backwards and upwards arrows but no forwards or downwards arrows...... galaxy brain

@darius I also love that basically nobody had lower case until ascii

Technically the 8-bit versions was never called ASCII, were they? There were variations called extended-ASCII but they were all different.

I think ISO 8859 wss only referred to as ASCII informally.

@loke @darius Yes. When documenting technological history, it's good to clarify that 80s and 90s people may have referred to anything ASCII-ish as ASCII, but I don't think we should be implying that there were multiple actual ASCIIs.

Barring the earlier revisions of ASCII, ASCII (ANSI X3.4-1977 and ANSI X3.4-1986, which I believe differ in wording but not in character mapping[0]) is one and only one complete mapping between 7-bit values and their interpretation as control codes or printable characters.

> Revision of ANSI X3.4-1977 [ . . . ]

> This standard was developed in parallel with its international counterpart ISO 646:1983 [ . . . ]‌ Differences in the U.S. (ANSI) version resulted from efforts to "adopt more customary U.S. terminology and to reduce ambiguity." [ . . . ]

@clacke @loke I agree that this is needed when documenting history, and I try to use such care in my blog, but I think that when I'm making a casual microblogging post I can say "256 character ASCII" and people know what I mean.

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