assume cs:codesg,ds:datasg
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: ;小写英文字母从a(61h)至z(7a)
mov cl,ds:[si] ;先判断字母区间[61h,7a],再做与操作
mov ch,0
jcxz return
cmp cl,61h
jb s0
cmp cl,7ah
ja s0
and ds:[si],11011111b
s0: inc si
jmp letterc
return: ret
codesg ends
end begin |
