解决了两个问题，还得再问一个新问题，王爽课程设计2的时钟显示更改程序逻辑后不会自动跳动

[feekee]

代码如下，跟第二个问题中的一摸一样。问题部分是因为按照课程设计，按2进入dos界面后，会把之前选择时的按键如3、2、F1等在c:\后显示出来，为了进入dos后不显示这些按键，计划在按2进入dos之前把这些按键对应的键盘缓冲都清掉。
那么，我不明白的是下面红色和绿色两种做法，都可以达到目的。但是如果按照红色的做法，注释掉绿色的部分，按3进入时钟显示界面后，时间会自己一直跳动；如下：

而如果把红色的部分注释掉，使用绿色的部分（即进入自定义的中断例程后一开始就删除键盘的缓冲），那么进入时钟界面后，时钟界面只显示一次当前的时间，时间不会跳动。想请教一下，不知道这个删除键盘缓冲区的位置怎么会对时钟显示有的影响？
assume cs:codesg,ds:datasg,ss:stacksg
datasg segment
db 4 dup (0)
datasg ends
stacksg segment
dw 32 dup (0)
stacksg ends
codesg segment
start:;write to the floppy
mov ax,cs
mov es,ax
mov bx,offset floppy

mov dl,0
mov dh,0
mov cl,1
mov ch,0
mov al,2
mov ah,3
int 13h

mov ax,4c00h
int 21h

org 7c00h
floppy:jmp short beg
origin_int9 dw 0,0
dis_choice db 0
is_clock db 0
format2 db 'YE/MO/DA hh:mm:ss',0
;mov ax,stacksg
;mov ss,ax
;mov sp,32*2
;mov ax,datasg
beg:;将第二个扇区读入内存
mov ax,0
mov es,ax
mov bx,7c00h+200h
mov dx,0
mov cx,2
mov ax,0201h
int 13h

mov dis_choice,1
call display

;替换9号中断
mov ax,0
mov es,ax
mov ax,es:[9*4]
mov origin_int9,ax
mov ax,es:[9*4+2]
mov origin_int9[2],ax

cli
mov word ptr es:[9*4],offset s9_beg
mov word ptr es:[9*4+2],cs
sti

s3:nop
jmp short s3

s9_beg:push bp
mov bp,sp
add bp,2
push ax
push ds
push bx
push si
push cx
push es
push di

in al,60h
mov bl,al
pushf
;mov si,offset origin_int9
call dword ptr origin_int9;here the book use 'cs' register

mov ah,0
int 16h
cmp bl,2h
je reset
cmp bl,3h
je sys
cmp bl,4
je clock
cmp is_clock,1
jne s10
cmp bl,3Bh
je c_f1
cmp bl,1h
jne s10
jmp near ptr c_esc
s10:jmp near ptr s4
reset:mov ax,ss
mov ds,ax
mov word ptr ds:[bp],0
mov word ptr ds:[bp+2],0ffffh
jmp near ptr s4
sys:;
;恢复int 9
mov ax,0
mov es,ax
mov ax,origin_int9
mov es:[9*4],ax
mov ax,origin_int9[2]
mov es:[9*4+2],ax
;删除键盘缓冲区
;mov ah,0
;int 16h
;int 13h 读硬盘
mov dx,0080h
mov cx,0001h
mov bx,7c00h
;es的值已设置过
mov ax,0201h
;模拟int 13h指令
pushf
;pushf
;pop ax
;and ah,11111100b
;push ax
;popf
push es
push bx
mov dis_choice,0
call display
jmp dword ptr es:[13h*4]
clock:mov is_clock,1
;mov ah,0
;int 16h
mov ax,ss
mov ds,ax
mov word ptr ds:[bp],offset clock_dis
mov ax,cs
mov word ptr ds:[bp+2],ax
mov dis_choice,0
call display
jmp short s4
c_f1:;mov ah,0
;int 16h
mov ax,0b800h
mov es,ax
mov di,160*12+62+1
mov si,0
cf1_s1:cmp byte ptr format2[si],0
je s4
add byte ptr es:[di],1
inc si
add di,2
jmp short cf1_s1
c_esc:;mov ah,0
;int 16h
mov is_clock,0
;清除屏幕先
mov ax,0b800h
mov es,ax
mov di,160*12+62
mov si,0
cesc_s1:cmp byte ptr format2[si],0
je cesc_s3
mov es:[di],0720h
inc si
add di,2
jmp short cesc_s1
cesc_s3:mov dis_choice,1
call display
mov ax,ss
mov ds,ax
mov word ptr ds:[bp],offset s3
mov ax,cs
mov word ptr ds:[bp+2],ax
jmp short s4
s4:pop di
pop es
pop cx
pop si
pop bx
pop ds
pop ax
pop bp
iret
s9_se:nop

;dis_choice为参数：1为显示,0为清屏
display:jmp short dis_beg
ad dw f1,f2,f3,f4
f1 db '1) reset pc',0
f2 db '2) start system',0
f3 db '3) clock',0
f4 db '4) set clock',0
dis_beg:push ax
push es
push di
push cx
push si
push bx
push dx
mov ax,0b800h
mov es,ax
mov cx,0 ;行数计数器
mov si,0 ;每行地址的指针
next:mov di,10*160+32*2
mov ax,160
mul cx
add di,ax

mov bx,ad[si]
add si,2
s0:mov al,cs:[bx]
cmp al,0 ;一行是否结束
je s1
add bx,1
;display功能选择
cmp dis_choice,1
je s2
mov byte ptr es:[di],' '
jmp short s5
s2:mov es:[di],al
s5:add di,2
jmp short s0
s1:add cx,1
cmp cx,4
je dis_end
jmp short next
dis_end:pop dx
pop bx
pop si
pop cx
pop di
pop es
pop ax
ret

clock_dis:jmp short s7
format db 'YE/MO/DA hh:mm:ss',0
position db 9,8,7,4,2,0
s7:mov bx,0
mov si,0
mov cx,6
s9:mov al,position[bx]
out 70h,al
in al,71h
mov ah,al
push cx
mov cl,4
shr ah,cl
pop cx
and al,00001111b

add ah,30h
add al,30h

mov format[si],ah
mov format[si+1],al
add si,3
inc bx
loop s9

mov ax,0b800h
mov es,ax
mov di,160*12+62
mov si,0
s8:cmp byte ptr format[si],0
je s7
mov al,format[si]
mov es:[di],al
inc si
add di,2
jmp short s8
codesg ends
end start

另外附上我在标号s7的地方加上下面的代码进行过的一次调试
mov ax,0b800h
mov es,ax
inc byte ptr es:[160*24+158]
观察按3以后s7是不是一直在执行。结果是右下角的符号每次按3会快速变化一下，然后就不变了。比如第一次按3后显示'G'，按esc退出第二次按3进去，变成一个乱码，然后再按esc再按3进入，又是变了一下就停了，如图。为啥每次都是只执循环限次数呢？这就是上面的问题

[feekee]

发现这样代码看上不去不清晰，但是使用[code]格式发的话，又没法对代码进行着色，所以按照代码格式再发一遍，大家可以对照位置看下面的代码，多谢

assume cs:codesg,ds:datasg,ss:stacksg
datasg segment
  db 4 dup (0)
datasg ends
stacksg segment
  dw 32 dup (0)
stacksg ends
codesg segment
  start:;write to the floppy
  		mov ax,cs
  		mov es,ax
  		mov bx,offset floppy
  		
  		mov dl,0
  		mov dh,0
  		mov cl,1
  		mov ch,0
  		mov al,2
  		mov ah,3
  		int 13h
  		
  		mov ax,4c00h
  		int 21h
 
 org 7c00h
 floppy:jmp short beg
origin_int9 dw 0,0
dis_choice db 0
is_clock db 0
format2 db 'YE/MO/DA hh:mm:ss',0
 		;mov ax,stacksg
  		;mov ss,ax
  		;mov sp,32*2
  		;mov ax,datasg
  	beg:;将第二个扇区读入内存
  		mov ax,0
  		mov es,ax
  		mov bx,7c00h+200h
  		mov dx,0
  		mov cx,2
  		mov ax,0201h
  		int 13h
  		
  		mov dis_choice,1
  		call display
  		
  		;替换9号中断
  		mov ax,0
   		mov es,ax
  		mov ax,es:[9*4]
  		mov origin_int9,ax
  		mov ax,es:[9*4+2]
  		mov origin_int9[2],ax
  		
  		cli
  		mov word ptr es:[9*4],offset s9_beg
   		mov word ptr es:[9*4+2],cs
   		sti
  		
   	 s3:nop
   		jmp short s3
   		
 s9_beg:push bp
 		mov bp,sp
 		add bp,2
 		push ax
 		push ds
 		push bx
 		push si
 		push cx
 		push es
 		push di
 		
 		in al,60h
		mov bl,al
 	 	pushf
 		;mov si,offset origin_int9
  		call dword ptr origin_int9;here the book use 'cs' register

  		mov ah,0
  		int 16h
  		cmp bl,2h
 		je reset
 		cmp bl,3h
 		je sys
 		cmp bl,4
 		je clock
 		cmp is_clock,1
 		jne s10
 		cmp bl,3Bh
 		je c_f1
 		cmp bl,1h
 		jne s10
 		jmp near ptr c_esc
 	s10:jmp near ptr s4
  reset:mov ax,ss
  		mov ds,ax
  		mov word ptr ds:[bp],0
  		mov word ptr ds:[bp+2],0ffffh
  		jmp near ptr s4
    sys:;
    	;恢复int 9
    	mov ax,0
    	mov es,ax
    	mov ax,origin_int9
  		mov es:[9*4],ax
  		mov ax,origin_int9[2]
  		mov es:[9*4+2],ax
  		;删除键盘缓冲区
  		;mov ah,0
  		;int 16h
  		;int 13h 读硬盘
    	mov dx,0080h
    	mov cx,0001h
    	mov bx,7c00h
    	;es的值已设置过
    	mov ax,0201h
    	;模拟int 13h指令
    	pushf
    	;pushf
    	;pop ax
    	;and ah,11111100b
    	;push ax
    	;popf
    	push es
    	push bx
    	mov dis_choice,0
    	call display
    	jmp dword ptr es:[13h*4]
  clock:mov is_clock,1
  		;mov ah,0
  		;int 16h
  		mov ax,ss
  		mov ds,ax
  		mov word ptr ds:[bp],offset clock_dis
  		mov ax,cs
  		mov word ptr ds:[bp+2],ax
  		mov dis_choice,0
  		call display
  		jmp short s4
   c_f1:;mov ah,0
  		;int 16h
   		mov ax,0b800h
        mov es,ax
        mov di,160*12+62+1
        mov si,0
 cf1_s1:cmp byte ptr format2[si],0
        je s4
        add byte ptr es:[di],1
        inc si
        add di,2
        jmp short cf1_s1
  c_esc:;mov ah,0
  		;int 16h
  		mov is_clock,0
		;清除屏幕先
  		mov ax,0b800h
        mov es,ax
        mov di,160*12+62
        mov si,0
cesc_s1:cmp byte ptr format2[si],0
        je cesc_s3
        mov es:[di],0720h
        inc si
        add di,2
        jmp short cesc_s1
cesc_s3:mov dis_choice,1
		call display
  		mov ax,ss
  		mov ds,ax
  		mov word ptr ds:[bp],offset s3
  		mov ax,cs
  		mov word ptr ds:[bp+2],ax
  		jmp short s4
     s4:pop di
     	pop es
     	pop cx
     	pop si
  		pop bx
  		pop ds
  		pop ax
  		pop bp
  		iret
  s9_se:nop
  
  ;dis_choice为参数：1为显示,0为清屏
  display:jmp short dis_beg
  ad dw f1,f2,f3,f4
  f1 db '1) reset pc',0
  f2 db '2) start system',0
  f3 db '3) clock',0
  f4 db '4) set clock',0  
  dis_beg:push ax
  	      push es
  	      push di
  	      push cx
  	      push si
  	      push bx
  	      push dx
  		  mov ax,0b800h
  		  mov es,ax
  		  mov cx,0	;行数计数器
  		  mov si,0	;每行地址的指针
  	 next:mov di,10*160+32*2
	      mov ax,160
	 	  mul cx
	      add di,ax

  	      mov bx,ad[si]
  		  add si,2
  	   s0:mov al,cs:[bx]
  		  cmp al,0	;一行是否结束
  		  je s1
  		  add bx,1
  		  ;display功能选择
  		  cmp dis_choice,1
  		  je s2
  		  mov byte ptr es:[di],' '
  		  jmp short s5
  	   s2:mov es:[di],al
  	   s5:add di,2
  		  jmp short s0
	   s1:add cx,1
	      cmp cx,4
	      je dis_end
	      jmp short next
  dis_end:pop dx
  		  pop bx
  		  pop si
  		  pop cx
  		  pop di
  		  pop es
  		  pop ax
  		  ret
  		  
clock_dis:jmp short s7
format db 'YE/MO/DA hh:mm:ss',0
position db 9,8,7,4,2,0
     s7:mov bx,0
        mov si,0
        mov cx,6
     s9:mov al,position[bx]
        out 70h,al
        in al,71h
        mov ah,al
        push cx
        mov cl,4
        shr ah,cl
        pop cx
        and al,00001111b
        
        add ah,30h
        add al,30h
        
        mov format[si],ah
        mov format[si+1],al
        add si,3
        inc bx
        loop s9
        
        mov ax,0b800h
        mov es,ax
        mov di,160*12+62
        mov si,0
     s8:cmp byte ptr format[si],0
        je s7
        mov al,format[si]
        mov es:[di],al
        inc si
        add di,2
        jmp short s8
codesg ends
end start

[feekee]

这不是个好问题，有点超出设计本身的范围了，先扔这里了，哪位大大路过看到了，帮俺解决了到时再结贴