Number of 0 in Binary

.MODEL SMALL
.STACK 100

.DATA

    M1 DB 'ENTER CHAR: $'
    M2 DB 0AH, 0DH, 'THE ASCII CODE OF: '
    C1 DB ?, 'IN BINARY IS: $'
    M3 DB 0AH, 0DH, 'THE NUMBER OF 0 BIT IS: '
    C2 DB ?, '$'

.CODE

MAIN PROC

    MOV AX, @DATA
    MOV DS, AX

    LEA DX, M1
    MOV AH, 9
    INT 21H

    MOV AH, 1
    INT 21H

    MOV BL, AL
    MOV C1, AL

    LEA DX, M2
    MOV AH, 9
    INT 21H

    MOV BH, 0
    MOV CX, 8

    MOV AH, 2

L1: SHL BL, 1
    JC L2
    MOV DL, '0'
    INT 21H
    INC BH
    JMP L3

L2: MOV DL, '1'
    INT 21H

L3: LOOP L1

    ADD BH, 30H
    MOV C2, BH

    LEA DX, M3
    MOV AH, 9
    INT 21H

    MOV AH, 4CH
    INT 21H

MAIN ENDP
END MAIN