<<On Fri, 23 Apr 2021 14:56:21 -0700, Paul Eggert via tz <tz@iana.org> said:
Yes, quite a few CPUs like that exist in the embedded world. And historically some mainframish CPUs had 9-, or even variable-width bytes. I put "theoretical interest" in that zic.c commit message only because as I understand it none of those CPUs are practical platforms for running zic today.
POSIX since 2001 requires eight-bit bytes, so the set of platforms this could possibly be relevant for is even smaller. (We only made it explicit in 2008, as I recall, but it was implicit in the requirement that uint8_t be defined, given the requirements C99 places on such a type when it exists.) There was a Unisys 36-bit operating system that was POSIX-certified for a previous edition of the standard (before the networking interfaces were merged, which was the proximate cause of requiring uint8_t). -GAWollman