According to Laussy Fabrice:

Is the way to tackle a part of code directly in code machine with GPC is to use RTL?

No: You write inline assembler code in the AT&T syntax. Yes: The interface between the assembler code and the Pascal program has a lot common with RTL. For documentation how to use assembler in GPC, see: ftp://agnes.dida.physik.uni-essen.de/gnu-pascal/contrib/gpcasm.zip Good luck, Peter -- Peter Gerwinski, Essen, Germany, free physicist and programmer Maintainer GNU Pascal - http://home.pages.de/~GNU-Pascal/ - 1 Oct 1997 PGP key fingerprint: AC 6C 94 45 BE 28 A4 96 0E CC E9 12 47 25 82 75 Fight the SPAM! - http://maps.vix.com/