C compilers and non-ASCII systems

A friend recently raised an issue with some code I wrote (a hex dump routine) saying it depended upon ASCII and thus, would break on non-ASCII based systems (and proposed a solution, but that's beside the issue here). I wrote back, saying the code in question was non-portable to begin with (since it depended upon read() and write()---it was targetted at Posix based systems) and besides, I've never encountered a non-ASCII system in the nearly 30 years I've been using computers. So now I'm wondering---besides Baudot, 6-bit BCD and EBCDIC, is there any other encoding scheme used? And of Baudot, 6-bit BCD and EBCDIC, are there any systems using those encoding schemes *AND* have a C compiler available? -spc (Or can I safely assume ASCII and derivatives these days?)