王爽汇编实验(十一）

 1 assume cs:codesg
 2 datasg segment
 3 db"Beginner's All-purpose Symbbolic Instruction Code.",0
 4 datasg ends
 5 codesg segment
 6 begin: mov ax,datasg
 7 mov ds,ax
 8 mov si,0
 9 call letterc
10 mov ax,4c00h
11 int 21h
12 letterc:
13 little:mov al,ds:[si]
14 mov cl,al
15 mov ch,0
16 jcxz ok
17 cmp cl,61H
18 jb s
19 cmp cl,7Ah
20 ja s
21 and cl,11011111B
22 mov ds:[si],cl
23 s:inc si
24 jmp little
25 ok:ret
26 codesg ends
27 end begin