• System calls are realized by assembler command
    	int	40h
    
  • Before the call eax should be set to the system function number.
  • Many functions require parameters. Parameters are passed in other registers (ebx,ecx,edx and so on). The number and the type of parameters are explained in the documentation for each function.
  • Many functions return result in the register eax, and some set up other registers also. Presence/absence of returned value is explained in the documentation for each function.
  • All registers except those with returned value preserve. (Including flags register eflags).