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