Uppercase, Lowercase

.MODEL LARGE
.STACK 100

.DATA

    MSG DB 'ENTER LOWERCASE CHARACTER: $'
    ANS DB 10, 13, 'UPPERCASE CHARACTER: '
    CHAR1 DB ?
    CHAR2 DB ?
    CHAR3 DB ?, '$'

.CODE

JOY PROC

    MOV AX, @DATA
    MOV DS, AX

    LEA DX, MSG
    MOV AH, 9
    INT 21H

    MOV AH, 1
    INT 21H
    SUB AL, 20H            ; UPPERCASE
    ;ADD AL, 20H           ; LOWERCASE
    MOV CHAR1, AL

    MOV AH, 1
    INT 21H
    SUB AL, 20H            ; UPPERCASE
    ;ADD AL, 20H           ; LOWERCASE
    MOV CHAR2, AL

    MOV AH, 1
    INT 21H
    SUB AL, 20H            ; UPPERCASE
    ;ADD AL, 20H           ; LOWERCASE
    MOV CHAR3, AL

    LEA DX, ANS
    MOV AH, 9
    INT 21H

    MOV AH, 4CH
    INT 21H

JOY ENDP
END JOY