assume cs:code,ds:datadata segment  db  'Beginners All-purpose Symbolic Instruction Code.',0data endscode segmentbegin:          mov ax,data          mov ds,ax          mov si,0          call letterc          mov ah,4ch          int 21hletterc:            push ax s:            mov al,[si]            mov ah,0            mov cx,ax            jcxz return            cmp al,61h            jb next            cmp al,91h            ja next            and al,11011111b            mov [si],alnext:            inc si            jmp short s return:            pop ax            retcode endsend begin