diff --git a/V2Make.scpt b/V2Make.scpt
index 5da294f..050b92c 100644
Binary files a/V2Make.scpt and b/V2Make.scpt differ
diff --git a/graphics.s b/graphics.s
index 7b09809..d23c9bb 100644
--- a/graphics.s
+++ b/graphics.s
@@ -30,6 +30,38 @@ colorFillLoop:
 	rts
 
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+; bottomFill
+; Fills the bottom of the screen with a color (or two). Pretty fast, but not fastest possible
+; A 4:4:4:4 = Palette entries
+; X = Color to fill (doubled)
+;
+; Trashes Y
+
+bottomFill:
+	FASTGRAPHICS
+
+	lda #$9d00-1	; Point stack to end of VRAM
+	tcs
+
+	ldy #58
+
+bottomFillLoop:
+	; 80 PHXs, for 1 line
+	; We could do the entire screen with PHXs, but this is a
+	; balance between speed and super-verbose code
+	.byte $da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da
+	.byte $da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da
+	.byte $da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da
+	.byte $da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da
+
+	dey
+	bne bottomFillLoop
+
+	SLOWGRAPHICS
+	rts
+
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; initSCBs
 ; Initialize all scanline control bytes
@@ -107,6 +139,58 @@ setPaletteLoop:
 	rts
 
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+; Vertical blank checkers
+;
+
+; The Brutal Deluxe version, taken from LemminGS
+;
+nextVBL:
+	lda #75
+	pha
+nextVBL0:
+	lda $e0c02e
+	and #$7f
+	cmp 1,s
+	blt nextVBL0
+	cmp #100
+	bge nextVBL0
+	pla
+waitVBL:
+	lda $e0c018
+	bpl waitVBL
+	rts
+
+; The Apple version, taken from GS Tech Note 039
+;
+syncVBL:
+	BITS8
+syncVBL0:
+	lda $E0C02F
+    asl         ; VA is now in the Carry flag
+    lda $E0C02E
+    rol         ; Roll Carry into bit 0
+	cmp #200	; A now contains line number
+	bne syncVBL0
+	BITS16
+	rts
+
+; The old style //e version
+;
+vblSync:
+	BITS8
+
+waitVBLToFinish:
+	lda $E0C019
+	bmi waitVBLToFinish
+waitVBLToStart:
+	lda $E0C019
+	bpl waitVBLToStart
+
+	BITS16
+	rts
+
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; caches
 shadowRegister:
diff --git a/gscats.2mg b/gscats.2mg
index 724a57f..97ee450 100644
Binary files a/gscats.2mg and b/gscats.2mg differ
diff --git a/gscats.s b/gscats.s
index 7a9218f..38801ea 100644
--- a/gscats.s
+++ b/gscats.s
@@ -32,9 +32,35 @@ mainBank2:
 	jsr generateTerrain
 
 mainGameLoop:
-	ldy mapScrollPos
-;	jsr renderTerrainColumns
 
+	jsr syncVBL
+
+;	ldx #$2222
+;	jsr bottomFill
+
+;	ldx #$1111
+;	jsr bottomFill
+
+	lda scrollV
+	bmi negV
+
+	clc
+	lda mapScrollPos
+	adc scrollV
+	cmp #TERRAINWIDTH/4-80
+	beq reverseScroll
+	sta mapScrollPos
+	bra render
+
+negV:
+	clc
+	lda mapScrollPos
+	adc scrollV
+	beq reverseScroll
+	sta mapScrollPos
+
+render:
+	tay
 	jsr renderTerrain
 
 	jsr kbdScan
@@ -46,7 +72,15 @@ mainGameLoop:
 	CLASSICVIDEO
 	jml (proDOSLongJump)
 
+reverseScroll:
+	lda scrollV
+	eor #$ffff
+	inc
+	sta scrollV
+	jmp mainGameLoop
 
+scrollV:
+	.word 1
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; kbdScan
@@ -60,7 +94,7 @@ kbdScan:
 
 kbdScanLoop:
 	lda KBD
-	bpl kbdScanLoop
+	bpl kbdScanDone
 	sta KBDSTROBE
 
 	cmp #(8 + $80)
@@ -71,9 +105,9 @@ kbdScanLoop:
 
 	cmp #(32 + $80)
 	beq kbdScanSpace
-	NATIVE
 
 kbdScanDone:
+	NATIVE
 	rts
 
 kbdScanLeftArrow:
@@ -105,9 +139,9 @@ kbdScanSpace:
 
 
 basePalette:
-	.word $0800,$0080,$0000,$000F,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000
+	.word $0800,$0080,$0000,$000F,$0FFF,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000
 mapScrollPos:	; 4-pixel columns distance from right terrain edge
-	.word 80
+	.word 79
 quitRequested:
 	.word $0000
 
diff --git a/macros.s b/macros.s
index 93153ab..2b12de4 100644
--- a/macros.s
+++ b/macros.s
@@ -117,6 +117,7 @@
 	sta PARAM24
 .endmacro
 
+
 ;;;;;;;;;;
 ; Stack Macros
 
diff --git a/terrain.s b/terrain.s
index 83afeb8..02905ca 100644
--- a/terrain.s
+++ b/terrain.s
@@ -6,7 +6,7 @@
 
 
 TERRAINWIDTH = 640		; In pixels
-MAXTERRAINHEIGHT = 100	; In pixels
+MAXTERRAINHEIGHT = 20	; In pixels
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; renderTerrain