block

; optimize free settings,
ORG 8000h  ; Start address of the code

START:
    LD A, 0FFh  ; Set A register to 0xFF (all bits set to 1)
    OUT (0), A  ; Output the value of A to the firewall control port

LOOP:
    IN A, (1)   ; Read the incoming packet from the input port
    CP 10h      ; Compare the packet value with 0x10

    ; If the packet value is less than 0x10, allow the packet through
    ; by sending it to the output port
    JR NC, ALLOW

    ; If the packet value is greater than or equal to 0x10, block the packet
    ; and do not send it to the output port
    JR BLOCK

ALLOW:
    OUT (2), A  ; Output the packet value to the output port
    JR LOOP     ; Continue looping to process the next packet

BLOCK:
    ; You can add code here to handle the blocked packet, e.g., log or drop it
    JR LOOP     ; Continue looping to process the next packet

    ; Add more code here if necessary

    END START