Blink LED program for DIGIT TMP68301 board

blink68k.asm

*	Title: Blink LED
*	Target: DIGIT TMP68301 BOARD
*	Assembler: https://archive.org/details/68000ASM_ZIP
*	Helper: http://takeda-toshiya.my.coocan.jp/msdos/
*	Win32 command: msdos asm -l blink68k.asm
*
*	Special thanks @comoneko on Twitter
*
IORBASE	equ	$00FFFC00
*
*	Address setting REGs
AMAR0	equ	IORBASE+$000
AMAR1	equ	IORBASE+$004
AAMR0	equ	IORBASE+$001
AAMR1	equ	IORBASE+$005
AACR0	equ	IORBASE+$003
AACR1	equ	IORBASE+$007
AACR2	equ	IORBASE+$009
ATOR	equ	IORBASE+$00B
ARELR	equ	IORBASE+$00C
*
*	Parallel interface REGs
PDIR	equ	IORBASE+$100
PCR	equ	IORBASE+$103
PSR	equ	IORBASE+$105
PCMR	equ	IORBASE+$107
PMR	equ	IORBASE+$109
PDR	equ	IORBASE+$10A
PPR1	equ	IORBASE+$10D
PPR2	equ	IORBASE+$10F
*
*	Reset vectors
	org	$00000000
RESVCT:	dc.l	$0040FFFC	Stack address
	dc.l	$00000400	Start address
*
*	main
	org	$00000400
START:	move.w	#$0000,CCR	IRQ disable
	move.b	#$00,D0		BERR disable
	move.b	D0,ATOR
*
*	RAM CS1
	move.b	#$40,D0		Address area
	move.b	D0,AMAR1
	move.b	#$FF,D0		No mask
	move.b	D0,AAMR1
	move.b	#$3D,D0		CS1 enable, Wait 5 clocks
	move.b	D0,AACR1
*
*	Parallel interface
	move.b	#$00,D0		Mode0 16bit simple IO
	move.b	D0,PCR
	move.w	#$FFFF,D0	Set all ports as output
	move.w	D0,PDIR
	move.w	#$0000,D0	Initialize as all ports H
	move.w	D0,PDR
*
LOOP1:	subi	#$1,D0		Change ports data
	move.w	D0,PDR
	bsr	DELAY		Wait
	bra	LOOP1		Repeat
*
DELAY:	move.l	#$0B000000,D1	Time constant
LOOP2:	subi	#$01,D1		Decrement
	bne	LOOP2		If not 0, repeat
	rts
*
	end