MYPORT	EQU	0x200000
	MOV	R0,#2_01010000	;R0=0x50 (01010000 in binary)
	LDR	R1,=MYPORT	;R1 = port address
OVER	LDRB	R2,[R1]		;get a byte from PORT and place it in R2
	TST	R2,R0		;are bits 4 and 6 LOW?
	BNE	OVER		;keep checking
	ADD	R4,R4,#1