Thursday, November 5, 2015

Why USS Supports only EBCDIC 1047?

So why is C designed for EBCDIC 1047? Because z/OS Unix Systems Services (USS) is also designed for it.

When IBM created USS for z/OS, it makes sense that it had to work in EBCDIC. The POSIX standard for UNIX doesn't require the use of ASCII, and z/OS is an EBCDIC operating system. IBM really didn't have a choice.

The problem is that UNIX, and its core programming language C, rely on characters that don't exist in some EBCDIC codepages.

EBCDIC 1047 is designed to include all the characters USS needs - effectively all the characters from Extended ASCII: ISO8859-1.

So EBCDIC 1047 is the default EBCDIC codepage used in USS.

 All parameter and help files are usually supplied in EBCDIC 1047, the C compiler expects code in EBCDIC 1047, and all UNIX file contents default to EBCDIC 1047.

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