Proof of concept for page flipping

2025-08-10 03:25:01 +00:00 · 2017-02-26 20:17:22 -08:00
parent 9284814222
commit 110760c8b1
5 changed files with 485 additions and 131 deletions
--- a/HiSprite.py
+++ b/HiSprite.py
@@ -162,10 +162,14 @@ def generateBlitter(colorStreams,maskStreams,height,xdraw):

 def rowStartCalculatorCode():
 	return \
-	"\tlda HGRROWS_H1,x\n" + \
+	"\tphy\n" + \
+	"\ttxa\n" + \
+	"\ttay\n" + \
+	"\tlda (HIRES_PAGE_L),y\n" + \
 	"\tsta SCRATCH1\n" + \
-	"\tlda HGRROWS_L,x\n" + \
+	"\tlda HGRROWS_L,y\n" + \
 	"\tsta SCRATCH0\n" + \
+	"\tply\n" + \
 	"\tldy PARAM0\n" + \
 	"\tlda DIV7_2,y\n" + \
 	"\ttay\n";		
--- a/graphics.s
+++ b/graphics.s
@@ -16,6 +16,42 @@ EnableHires:
 	lda HIRES2
 	rts

+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+; WritePage1
+; Trashes A
+;
+WritePage1:
+	lda #<HGRROWS_H1
+	sta HIRES_PAGE_L
+	lda #>HGRROWS_H1
+	sta HIRES_PAGE_H
+	rts
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+; WritePage2
+; Trashes A
+;
+WritePage2:
+	lda #<HGRROWS_H2
+	sta HIRES_PAGE_L
+	lda #>HGRROWS_H2
+	sta HIRES_PAGE_H
+	rts
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+; PageFlip
+; Trashes A
+;
+PageFlip:
+	lda RDPAGE2
+	bmi PageFlip_Show1
+	lda HIRESPAGE2
+	jmp WritePage1
+
+PageFlip_Show1:
+	lda HIRESPAGE1
+	jmp WritePage2
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; SaveBackground
 ; PARAM0: X pos
@@ -37,21 +73,24 @@ saveBackground_loop:
 	pha
 	adc	PARAM1	; Calculate Y line
 	tax
+	phy
+	tay

-	lda HGRROWS_H1,x			; Compute hires row
+	lda (HIRES_PAGE_L),y			; Compute hires row
 	sta saveBackground_smc0+2
 	sta saveBackground_smc1+2
 	sta saveBackground_smc2+2
 	sta saveBackground_smc3+2
 	sta saveBackground_smc4+2
 	sta saveBackground_smc5+2
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta saveBackground_smc0+1
 	sta saveBackground_smc1+1
 	sta saveBackground_smc2+1
 	sta saveBackground_smc3+1
 	sta saveBackground_smc4+1
 	sta saveBackground_smc5+1
+	ply

 	ldx PARAM0				; Compute hires column
 	lda DIV7_2,x
@@ -120,21 +159,24 @@ restoreBackground_loop:
 	pha
 	adc	PARAM1	; Calculate Y line
 	tax
+	phy
+	tay

-	lda HGRROWS_H1,x			; Compute hires row
+	lda (HIRES_PAGE_L),y			; Compute hires row
 	sta restoreBackground_smc0+2
 	sta restoreBackground_smc1+2
 	sta restoreBackground_smc2+2
 	sta restoreBackground_smc3+2
 	sta restoreBackground_smc4+2
 	sta restoreBackground_smc5+2
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta restoreBackground_smc0+1
 	sta restoreBackground_smc1+1
 	sta restoreBackground_smc2+1
 	sta restoreBackground_smc3+1
 	sta restoreBackground_smc4+1
 	sta restoreBackground_smc5+1
+	ply

 	ldx PARAM0				; Compute hires column
 	lda DIV7_2,x
--- a/hisprite.dsk
+++ b/hisprite.dsk
--- a/hisprite.s
+++ b/hisprite.s
@@ -14,7 +14,9 @@
 TEXT = $c050
 HIRES1 = $c057
 HIRES2 = $c058
-
+HIRESPAGE1 = $c054
+HIRESPAGE2 = $c055
+RDPAGE2 = $c01c

 ; ROM entry points
 COUT = $fded
@@ -75,10 +77,7 @@ main:
 ;	sta PARAM1
 ;	jsr BloadHires

-	lda #<HGRROWS_H1
-	sta HIRES_PAGE_L
-	lda #>HGRROWS_H1
-	sta HIRES_PAGE_H
+	jsr WritePage2

 	ldx #0
 ;;;;
@@ -103,10 +102,23 @@ loop:
 	lda #0
 	sta PARAM1

-	lda #<bgBuffer
+	lda RDPAGE2
+	bmi loop_SavePage1
+
+loop_SavePage2:
+	lda #<bgBuffer2
 	sta PARAM2
-	lda #>bgBuffer
+	lda #>bgBuffer2
 	sta PARAM3
+	bra loop_SavePage
+
+loop_SavePage1:
+	lda #<bgBuffer1
+	sta PARAM2
+	lda #>bgBuffer1
+	sta PARAM3
+
+loop_SavePage:
 	jsr SaveBackground

 	jsr BOXW_MAG
@@ -114,13 +126,34 @@ loop:
 	jsr ROMWAIT

 	; Sync to VBL
-@1: lda $C019
-	beq @1
-	bpl @1
-@0:	lda $C019
-	bmi @0
+;@1: lda $C019
+;	beq @1
+;	bpl @1
+;@0:	lda $C019
+;	bmi @0

+	jsr PageFlip
+
+	lda RDPAGE2
+	bmi loop_RestorePage1
+
+loop_RestorePage2:
+	lda #<bgBuffer2
+	sta PARAM2
+	lda #>bgBuffer2
+	sta PARAM3
+	bra loop_RestorePage
+
+loop_RestorePage1:
+	lda #<bgBuffer1
+	sta PARAM2
+	lda #>bgBuffer1
+	sta PARAM3
+
+loop_RestorePage:
+	dec PARAM0
 	jsr RestoreBackground
+	inc PARAM0

 	inx
 	cpx #133
@@ -130,7 +163,7 @@ loop:

 	rts

-bgBuffer:
+bgBuffer1:
 	.byte 0
 	.byte 0
 	.byte 0
@@ -180,6 +213,57 @@ bgBuffer:
 	.byte 0
 	.byte 0

+bgBuffer2:
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+
+
 bgFilename:
 	.byte "KOL",0

--- a/spritegen0.s
+++ b/spritegen0.s
@@ -20,10 +20,14 @@ BOXW_MAG_JMP:

 BOXW_MAG_SHIFT0:
 	ldx PARAM1
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -47,10 +51,14 @@ BOXW_MAG_SHIFT0:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -74,10 +82,14 @@ BOXW_MAG_SHIFT0:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -101,10 +113,14 @@ BOXW_MAG_SHIFT0:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -128,10 +144,14 @@ BOXW_MAG_SHIFT0:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -155,10 +175,14 @@ BOXW_MAG_SHIFT0:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -182,10 +206,14 @@ BOXW_MAG_SHIFT0:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -209,10 +237,14 @@ BOXW_MAG_SHIFT0:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -242,10 +274,14 @@ BOXW_MAG_SHIFT0:

 BOXW_MAG_SHIFT1:
 	ldx PARAM1
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -269,10 +305,14 @@ BOXW_MAG_SHIFT1:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -296,10 +336,14 @@ BOXW_MAG_SHIFT1:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -323,10 +367,14 @@ BOXW_MAG_SHIFT1:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -350,10 +398,14 @@ BOXW_MAG_SHIFT1:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -377,10 +429,14 @@ BOXW_MAG_SHIFT1:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -404,10 +460,14 @@ BOXW_MAG_SHIFT1:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -431,10 +491,14 @@ BOXW_MAG_SHIFT1:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -464,10 +528,14 @@ BOXW_MAG_SHIFT1:

 BOXW_MAG_SHIFT2:
 	ldx PARAM1
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -491,10 +559,14 @@ BOXW_MAG_SHIFT2:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -518,10 +590,14 @@ BOXW_MAG_SHIFT2:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -545,10 +621,14 @@ BOXW_MAG_SHIFT2:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -572,10 +652,14 @@ BOXW_MAG_SHIFT2:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -599,10 +683,14 @@ BOXW_MAG_SHIFT2:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -626,10 +714,14 @@ BOXW_MAG_SHIFT2:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -653,10 +745,14 @@ BOXW_MAG_SHIFT2:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -686,10 +782,14 @@ BOXW_MAG_SHIFT2:

 BOXW_MAG_SHIFT3:
 	ldx PARAM1
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -713,10 +813,14 @@ BOXW_MAG_SHIFT3:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -740,10 +844,14 @@ BOXW_MAG_SHIFT3:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -767,10 +875,14 @@ BOXW_MAG_SHIFT3:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -794,10 +906,14 @@ BOXW_MAG_SHIFT3:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -821,10 +937,14 @@ BOXW_MAG_SHIFT3:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -848,10 +968,14 @@ BOXW_MAG_SHIFT3:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -875,10 +999,14 @@ BOXW_MAG_SHIFT3:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -908,10 +1036,14 @@ BOXW_MAG_SHIFT3:

 BOXW_MAG_SHIFT4:
 	ldx PARAM1
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -935,10 +1067,14 @@ BOXW_MAG_SHIFT4:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -962,10 +1098,14 @@ BOXW_MAG_SHIFT4:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -989,10 +1129,14 @@ BOXW_MAG_SHIFT4:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1016,10 +1160,14 @@ BOXW_MAG_SHIFT4:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1043,10 +1191,14 @@ BOXW_MAG_SHIFT4:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1070,10 +1222,14 @@ BOXW_MAG_SHIFT4:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1097,10 +1253,14 @@ BOXW_MAG_SHIFT4:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1130,10 +1290,14 @@ BOXW_MAG_SHIFT4:

 BOXW_MAG_SHIFT5:
 	ldx PARAM1
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1157,10 +1321,14 @@ BOXW_MAG_SHIFT5:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1184,10 +1352,14 @@ BOXW_MAG_SHIFT5:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1211,10 +1383,14 @@ BOXW_MAG_SHIFT5:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1238,10 +1414,14 @@ BOXW_MAG_SHIFT5:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1265,10 +1445,14 @@ BOXW_MAG_SHIFT5:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1292,10 +1476,14 @@ BOXW_MAG_SHIFT5:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1319,10 +1507,14 @@ BOXW_MAG_SHIFT5:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1352,10 +1544,14 @@ BOXW_MAG_SHIFT5:

 BOXW_MAG_SHIFT6:
 	ldx PARAM1
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1379,10 +1575,14 @@ BOXW_MAG_SHIFT6:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1406,10 +1606,14 @@ BOXW_MAG_SHIFT6:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1433,10 +1637,14 @@ BOXW_MAG_SHIFT6:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1460,10 +1668,14 @@ BOXW_MAG_SHIFT6:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1487,10 +1699,14 @@ BOXW_MAG_SHIFT6:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1514,10 +1730,14 @@ BOXW_MAG_SHIFT6:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay
@@ -1541,10 +1761,14 @@ BOXW_MAG_SHIFT6:
 	sta (SCRATCH0),y

 	inx
-	lda HGRROWS_H1,x
+	phy
+	txa
+	tay
+	lda (HIRES_PAGE_L),y
 	sta SCRATCH1
-	lda HGRROWS_L,x
+	lda HGRROWS_L,y
 	sta SCRATCH0
+	ply
 	ldy PARAM0
 	lda DIV7_2,y
 	tay