INT 21,4C - Terminate Process With Return Code
AH = 4C AL = return code (for batch files) returns nothing - approved method of program termination - restores the terminate, Ctrl-Break, and critical error exit addresses, flushes all buffers, frees memory and returns to DOS via the termination handler address - does not close FCBs - this function is not supported in versions of DOS before 2.x, so use INT 21,0 or INT 20 to exit. - see also INT 27 INT 21,31