51.asm

来自「本书为清华大学第二版汇编语言的课后题详解」· 汇编 代码 · 共 47 行

;51.asm

codesg    segment
main    proc    far
        assume  cs:codesg
start:
        push    ds
        sub     ax,ax
        push    ax

next:   mov     ah,01
        int     21h
        
        cmp     al,61h
        jl      exit

        cmp     al,7ah
        jg      exit

        mov     bl,al
        mov     dl,0dh
        mov     ah,02
        int     21h

        mov     dl,0ah
        mov     ah,02
        int     21h

        sub     bl,20h
        mov     dl,bl
        mov     ah,02
        int     21h

        mov     dl,0dh
        mov     ah,02
        int     21h

        mov     dl,0ah
        mov     ah,02
        int     21h

        jmp     short   next
exit:   ret
main    endp
codesg  ends
        end    start