Assembly, IBM, Microprocessor, Programming, Coding.
INT 21H. Function code 09h is just one of them (i.e., to output a string). Lines 20, 21 are used to exit the program. In MS-DOS on 8086, we save the return code for a program in AL register. Then we call the interrupt with function code 4Ch in AH. In line 20 we are directly moving 4C00h into AX,