According to Frank Heckenbach:

According to myself (Peter Gerwinski):

...

You can get this information at run-time - and *only* at run-time since one and the same executable can run both on DOS (with and without DPMI) and on OS/2. If the variable `__osmode' contains a nonzero value, it is OS/2; if it is DOS and the variable `__emx_env' and $0180 is nonzero, it is DPMI (RSX).

But still I don't know how to get the system time in OS/2 or non-DPMI DOS [...]

This was implied: If `__osmode' is zero and `__emx_env' and $0180 is zero as well, then it is DOS without DPMI. Once again the three EMX modes as a tabular: __osmode __emx_env and $0180 system nonzero doesn't matter OS/2 0 nonzero DOS with DPMI 0 0 DOS without DPMI (-; Peter Dipl.-Phys. Peter Gerwinski, Essen, Germany, free physicist and programmer peter.gerwinski@uni-essen.de - http://home.pages.de/~peter.gerwinski/ [970201] maintainer GNU Pascal [970714] - http://home.pages.de/~gnu-pascal/ [970125]