> OK now, so I think you answered my question about interupts in Linux
> (a.k.a. UNIX.) But are interupts called on the microcode level, so
> that int 21 will be the same on all IBM 'puters?  Or can the OS
> developers name int 21 somthing else?  Is assembly the same on all
> OS's if there on IBM's.  Kind of a weird question, I hope it fits
> here.
INT 21 is a DOS call, hooked in by IO.SYS at boot time. It is
a vector in low memory, at 0:84, pointing to code loaded higher
in memory. No, assembly is not the same between OS's. What you
are refering to is called portability, and assembly is far from
portable.   
--- ifmail-tx (i386 Linux)
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