stack segment
    dw 512 dup(?)
stack ends
data segment

music_freq    dw 262,294,330,350,393,441
        dw 495,525,589,661,700,786
        dw 882,990,1112,1248
music_time    dw 800
        messg1 db 'Thank you for using it','$'
         messg2 db 0ah,0dh,'it is a music program','$'
            messg3 db 0ah,0dh,'please choose mode(Q:exit other key:continue)','$'
            messg4 db 0ah,0dh,'input error!$'
                messg5 db 0ah,0dh,'you can play the music now(key:0-F,Q:exit the program)!','$'
            messg6 db 0ah,0dh,'$'
        messg7 db 0ah,0dh,'thank you for using it,any key to exit!','$'
data ends

code segment
assume cs:code,ds:data,ss:stack
main proc far
start:
    mov ax,data
    mov ds,ax
    mov ax,stack
    mov ss,ax
    lea dx,messg1
    mov ah,09h
    int 21h
    lea dx,messg2
    mov ah,09h
    int 21h
    lea dx,messg3
    mov ah,09h
    int 21h
input: mov ah,01h
    int 21h
    cmp al,'Q'
    jz exit
    lea dx,messg5
    mov ah,09h
    int 21h
        lea dx,messg6
    mov ah,09h
    int 21h

l1:    mov ah,01h
    int 21h
    cmp al,'Q'
    jz exit1
    cmp al,30h
    jb error
    cmp al,46h
    ja error
    cmp al,40
    jb num
    jmp abcdef

num: sub al,30h
     mov dl,2
     mul dl
     lea bx,music_freq
     mov si,ax
     mov cx,[bx+si]
     mov dx,800
     call gensound
     jmp l1

abcdef: sub al,31h
        mov dl,2
        mul dl
        lea bx,music_freq
        mov si,ax
        mov cx,[bx+si]
        mov dx,800
        call gensound
        jmp l1
        
error:  lea dx,messg4
    mov ah,09h
    int 21h
    jmp l1
exit:    mov ah,4ch
    int 21h
exit1:  lea dx,messg7
    mov ah,09h
    int 21h
        mov ah,01h
    int 21h
    mov ah,4ch
    int 21h
main endp


gensound proc near
    push dx
    mov al,0b6h
    out 43h,al
    mov dx,8h
    mov ax,3208h
    div cx
    out 42h,al
    mov al,ah
    out 42h,al
    in al,61h
    mov ah,al
    or al,3
    out 61h,al
l3:    push dx
    push ax
    mov dx,8h
    mov ax,0f05h
s1:    sub ax,1
    sbb dx,0
    jnz s1
    pop ax
    pop dx
    dec bx
    jnz l3

    mov al,ah
    out 61h,al
    pop dx
    ret
gensound endp
code ends
end start






在l1循环那里，执行的速度太慢了。不知道怎么回事，或者怎么改？作用就是输入0-9和A-F得到对应的music-freq里的数字输入到CX里