Code:
	XDEF	Entry
	XREF	__SEG_END_SSTACK
Constants:		Section
ARRAY		dc.b	$EB,$77,$7B,$7D,$B7,$BB,$BD,$D7,$DB,$DD,$E7,$ED,$7E,$BE,$DE,$EE,$00
INDEX		ds.w	1
val		ds.b	1

Code:			Section
Entry:
		LDX	#ARRAY	;start X at begging of array
		LDY	#ARRAY	;this will allow us to subtract and find the index
Main:
		LDAA	1,X+		;load the first byte into acc. A
		CMPA	#$00		;the value was not found
		BEQ	NotFound

		CMPA	val		;check if A is equal to the value
		BNE	Main		;repeat the loop if it is not

		CMPA	val		;check if A is equal to the value
		BEQ	Found

Found:
		TFR	X,D		;store the value of x in acc. D
		SUBD	#ARRAY	;subtract the the value of the start of the array from D
NotFound:
		STAA	#$FF