.model small
.stack 100h
.data

a db 'InputLowercase letter: $'
b db 'Uppercase letter: $'

.code

main proc

    mov ax,@data
    mov ds,ax

    mov ah,9
    lea dx,a
    int 21h

    mov ah,1
    int 21h
    mov bl,al

    mov ah,2
    mov dl,10
    int 21h
    mov dl,13
    int 21h

    mov ah,9
    lea dx,b
    int 21h

    mov ah,2
    sub bl,32
    mov dl,bl
    int 21h

    exit:
    mov ah,4ch
    int 21h
    main endp
end main