1 assume cs:code
2 ;在屏幕处显示字符'a'变化到'z',并随时接受按键esc变化其颜色属性
3 stack segment
4 db 128 dup(0)
5 stack ends
6
7 data segment
8 dw 0,0
9 data ends
10
11 code segment
12 start:
13 mov ax,stack
14 mov ss,ax
15 mov sp,128
16
17 mov ax,data
18 mov ds,ax
19
20 mov ax,0
21 mov es,ax
22
23 push es:[9*4]
24 pop ds:[0]
25 push es:[9*4+2]
26 pop ds:[2] ;把程序结束前需归还的原按键例程入口地址储存到数据段
27
28 mov word ptr es:[9*4],offset int9
29 mov es:[9*4+2],cs ;设置中断例程入口地址
30
31 mov ax,0b800h
32 mov es,ax
33 mov ah,'a'
34 s:
35 mov es:[12*160+40*2],ah
36 call delay
37 inc ah
38 cmp ah,'z'
39 jna s ;在屏幕上显示从字符'a'到'z'
40
41 mov ax,0
42 mov es,ax
43
44 push ds:[0]
45 pop es:[9*4]
46 push ds:[2]
47 pop es:[9*4+2] ;把原按键例程的入口地址归还给向量的中断向量表
48
49 mov ax,4c00h
50 int 21h
51
52 delay: ;延迟子程序
53 push ax
54 push dx
55 mov dx,10h
56 mov ax,0
57 s1:
58 sub ax,1
59 sbb dx,0
60 cmp ax,0
61 jne s1
62 cmp dx,0
63 jne s1
64 pop dx
65 pop ax
66 ret
6x
67 int9: ;新int9中断例程
68 push ax
69 push bx
70 push es
71
72 in al,60h //从接口卡芯片处等待接受按键信息
73
74 pushf
75 call dword ptr ds:[0] ;精简的2行代码
76 cmp al,1
77 jne int9ret
78 mov ax,0b800h
79 mov es,ax
80 inc byte ptr es:[12*160+40*2+1] ;字符颜色变化
81
82 int9ret:
83 pop es
84 pop bx
85 pop ax
86 iret
87
88 code ends
89
90 end start
