Hello, The attached modifies i386-tdep.c so that there is a ``set i386 real-mode'' command (doco to go). When real-mode is enabled, GDB computes the ``20 bit'' ``stop address'' (aka PC but not to be confused with $pc ... :-) from both the $cs and $pc registers. That way, core GDB sees a cannonical PC address that (regardless of $cs) will match a ``20 bit'' breakpoint address. Thoughts? I'm desperatly trying to come up with a test-case mind. This is a rewrite of an old old patch (that hacked breakpoint.c) and the original testcase has been lost :-( Andrew