Hi, I'm making binary format programs with "use64" option. Fasm generates a .BIN file, I rename it to .EXE and I test it with the debug that comes with XP (debug.exe) but code is not legible becouse "use64" option.
If I use "use16" option there's no problem and the code is correct, so where can I get a 64 bit debugger.
I'm using XP 32 bits.

Another question is how the processor knows that the code is 16, 32 or 64 bits ?, if I open the binary file (that fasm creates) with a hex editor I see the code of the instrucctions (Mov, Lea, Add, so on) but no code for the use16/32/64 option, so how the processor knows the kinf of code ?

You can't really debug 64-bit code under 32-bit OS
The only way is to emulate it all, but generally debuggers rely on just-in-time execution of the program at hand. Find a 64-bit OS or just boot some 64-bit OS in QEMU and execute your code there. The latter one means A LOT of pain.

The second question is what is answered when you do some assembly A few weeks help I guess. The most basic explanation is that when you put USE16 in your code, then your other code must prepare CPU for this mode. Same goes for USE64. Usually in 64-bit Windows you don't use other code than 64-bit, but exceptions exist...

Thanks alot.