*	Scroll example ( fixed )

*	Hit left mouse button to quit


INTREQR		equ	$01e
INTREQ		equ	$09c
INTENAR		equ	$01c
INTENA		equ	$09a

DMACONR		equ	$002
DMACON		equ	$096

BPLCON0		equ	$100
BPLCON1		equ	$102
BPLCON2		equ	$104
BPL1MOD		equ	$108
BPL2MOD		equ	$10a

DDFSTRT		equ	$092
DDFSTOP		equ	$094
DIWSTRT		equ	$08e
DIWSTOP		equ	$090

BPL1PTH		equ	$0e0
BPL2PTH		equ	$0e4



LONG	DispMem Count
WORD	IntSave DmaSave Color


	DispMem = AllocMem( 16000 $10002 )
	beq	Quit
			
	a3 = $dff000
	IntSave = INTENAR(a3)	;save DMA and interrupt states
	DmaSave = DMACONR(a3)


*  set up display regs

	BPLCON0(a3) = $1200	; (LORES) 1BPL COLOR			
			
	BPLCON1(a3) = 0 w
	BPLCON2(a3) = 0 w
	BPL1MOD(a3) = 0 w
	BPL2MOD(a3) = 0 w

	DIWSTRT(a3) = $2c81
	DIWSTOP(a3) = $f4c1
	DDFSTRT(a3) = $0038 w
	DDFSTOP(a3) = $00d0 w

	INTENA(a3) = $7fff
	DMACON(a3) = $7fff
	INTENA(a3) = $8020	;SET VERTB
	DMACON(a3) = $8300	;SET DMAEN BPLEN

*  Make bands for effect

	d1 = 7
	d2 = $ffffffff
	a1 = DispMem
1$	d0 = 249
2$	(a1)+ = d2
	dbf	d0,2$
	a1 += 1000	;start of next band
	dbf	d1,1$

	d2 = DispMem
	d3 = d2
	d3 += 7960

VBloop	d1 = INTREQR(a3) w
	d1:5 = 1 {

		INTREQ(a3) = $0020 w

		d2 > d3 {
			d2 = DispMem
		} else {
			d2 += 80	;Scroll speed, try 40 * n
		}

		BPL1PTH(a3) = d2
	}

	($bfe001):6 = 1 VBloop

Quit
	DispMem != 0 {		
		FreeMem( DispMem 16000 )
	}

*	restore DMACON & INTENA
			
	a3 = $dff000
	INTENA(a3) = $7fff
	DMACON(a3) = $7fff
		
	d0 = IntSave
	bset.l	#15,d0
	INTENA(a3) = d0 w
			
	d0 = DmaSave
	bset.l	#15,d0
	DMACON(a3) = d0 w


	END