assembly code

__asm{ int portSWITCH_INT_NUMBER } This is from SourceportableoWotcom16BitDOSPCportmacro.h portSWITCH_INT_NUMBER  0x80 What does this mean?What is function of this?

assembly code

It simply puts the assembler instructions: int 0x80 in your code.  This is used to call the scheduler. Look up the ‘int’ instruction in an x86 instruction set manual. Regards.