Since I am under xp64 I'd like to know how to convert to 64 bit the sources.
I.E. what should I add -or remove- to kelvar.asm to make the exe work under xp64 ?

Thanks.

grab intel manuals, and follow this:

http://x86asm.net/articles/x86-64-tour-of-intel-manuals/index.html

also check this: http://www.jorgon.freeserve.co.uk/GoasmHelp/64bits.htm

IIRC then kelvar is for DOS. You will likely have incredible difficulty running any DOS app in a 64bit environment, especially something like kelvar that expects to switch the CPU into unReal mode. 64bit mode and unReal mode are not in any way compatible. You can't run both together, no how, no chance.

Thanks