li1.asm

本程序是汇编语言的一些基本功能的组合

code segment
 assume cs:code
main proc far
start:
 push ds
 sub ax,ax
 push ax

 mov ax,data
 mov ds,ax
XH:
 mov ah,1
 int 21h
 
 cmp al,0dh
 je exit
 
 cmp al,'a'
 jb done
 cmp al,'z'
 jnbe done
 
 sub al,32

DONE:
 mov dl,al
 mov ah,2
 int 21h
 jmp XH 

exit:
 ret
main endp
code ends
 end start