Microprocessor lab external-2

          The program that I had got in interfacing part was an ALP to perform logical XOR operation.The reason for me writing this program is very simple.Later in life whenever I recall microprocessor lab external and if I am not able to recall which program I had got,my blogpost will be there to help me recollect the question as well as the answer.

    Here is the solution for above mentioned question:

Data segment

Pa equ 0e800h

Pb equ 0e801h

Pc equ 0e802h

Cr equ 0e803h

Data ends

Code segment 

Assume cs:code,ds:data

Start:mov ax,data

        Mov ds,ax

        Mov al,082h

        Mov dx,cr

        Out dx,al

Repeat:mov dx,pb

            In al,dx

            And al,03h

            Cmp al,00h

            Jz display

             Cmp al,03h

             Jz display

             Mov al,0ffh

             Mov dx,pa

              Out dx,al

              Jmp repeat

Display:mov al,00h

             Mov dx,pa

             Out dx,Al

              Jmp repeat

Code ends 

End start