.EQU LED_PORT_1 = 0x033 ; port for output 1
.EQU SWITCH_PORT_1 = 0x99 ; port for input 1
.EQU LED_PORT_2 = 0xA7 ; port for output 2
.EQU SWITCH_PORT_2 = 0x0B8 ; port for input 2
.CSEG
.ORG 0x01 ; program starts here

main:   IN  R0, SWITCH_PORT_1
        LSR R0  ; shift right twice to divide by four
        LSR R0
        OUT R0, LED_PORT_1

        IN   R1, SWITCH_PORT_2
        EXOR R1, 0xFF ; take two's compliment
        ADD  R1, 0x01
        OUT  R1, LED_PORT_2

        BRN main ; endless loop