dec to octal

.model small
.stack 100h
.data
  msg1 db 0dh,0ah,'Do U want to convert or exit? Enter Y or N: $'
  msg2 db 0dh,0ah,'How many digits your number has? $'
  msg3 db 0dh,0ah,'Result in Octal: $'
  msg4 db 0dh,0ah,'Invalid $'
  msg5 db 0dh,0ah,'Enter the decimal number: $'
  msg6 db 0dh,0ah,'Enter the 1st Digit: $'
  msg7 db 0dh,0ah,'Enter the 2nd Digit: $'

.code
main proc

    mov ax,@data
    mov ds,ax

    option:

        mov ah,9
        lea dx, msg1
        int 21h

        mov ah,1
        int 21h;Enter y or n

        cmp al,'y'
        je y
        cmp al,'Y'
        je y
        jmp n

        y:
            mov ah,9
            lea dx,msg2
            int 21h

            mov ah,1
            int 21h

            cmp al,'1'
            je one
            cmp al,'2'
            je two
            jmp invalid

            one:
               mov ah,9
               lea dx,msg5
               int 21h

               mov ah,1
               int 21h
               mov bh,al
               cmp bh, 30h
               jl n
               cmp bh,'7'
               jg one_2
               mov ah,9
               lea dx,msg5
               int 21h
               mov ah,2
               mov dl, bh
               int 21h
               jmp option

               one_2:
                    cmp bh,38h
                    je cont
                    cmp bh, 39h
                    je cont

                    cont:
                        mov ah,9
                        lea dx, msg3
                        int
                        mov ah,2
                        mov dl,'1'
                        int 21h
                        sub bh,8
                        mov dl,bh
                        int 21h
                        jmp option

            two:

                mov ah,9
                lea dx,msg6
                int 21h

                mov ah,1
                int 21h
                mov bh,al;for 1st digit

                mov ah,9
                lea dx,msg7
                int 21h

                mov ah,1
                int 21h
                mov ch,al;for 2nd digit

                cmp bh,'1'
                je t1
                cmp bh,'2'
                je t2
                jmp invalid


            t1:

                cmp ch,'0'
                jge c1
                jmp c2

                c1:
                cmp ch,'5'
                jle l1
                jmp c2
                    l1:
                        add ch,2
                        mov ah,9
                        lea dx,msg3
                        int 21h
                        mov ah,2
                        mov dl,'1'
                        int 21h
                        mov dl,ch
                        int 21h
                        jmp option

                c2:
                        sub ch,6
                        mov ah,9
                        lea dx,msg3
                        int 21h
                        mov ah,2
                        mov dl,'2'
                        int 21h
                        mov dl,ch
                        int 21h
                        jmp option


            t2:
              cmp ch,'0'
              jg invalid
              mov ah,9
              lea dx,msg3
              int 21h
              mov ah,2
              mov dl,'2'
              int 21h
              mov dl,'4'
              int 21h
              jmp option


    invalid:
           mov ah,9
           lea dx,msg4
           int 21h
           jmp option



    n:

       mov ah,4ch
       int 21h



    main endp
end main