汇编语言实验11（王爽）编写子程序

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assume cs:codesg
datasg segment
db “Beginner’s All-purpose Symbolic Instruction Code.”,0
datasg ends
codesg segment
begin:mov ax,datasg
mov ds,ax
mov si,0
call letterc
mov ax,4c00h
int 21h
letterc:mov cl,[si]
mov ch,0
jcxz ok
cmp cl,‘a’
jb s0
cmp cl,‘z’
ja s0
and cl,11011111b
mov [si],cl
s0:inc si
jmp short letterc
ok:ret
codesg ends
end begin