diff --git a/engine/video.asm b/engine/video.asm
new file mode 100644
index 000000000..0d0aa272d
--- /dev/null
+++ b/engine/video.asm
@@ -0,0 +1,487 @@
+; Functions dealing with VRAM.
+
+DMATransfer: ; 15d8
+; Return carry if the transfer is completed.
+
+	ld a, [hDMATransfer]
+	and a
+	ret z
+
+; Start transfer
+	ld [rHDMA5], a
+
+; Execution is halted until the transfer is complete.
+
+	xor a
+	ld [hDMATransfer], a
+	scf
+	ret
+; 15e3
+
+
+UpdateBGMapBuffer: ; 15e3
+; Copy [$ffdc] 16x8 tiles from BGMapBuffer
+; to bg map addresses in BGMapBufferPtrs.
+
+; [$ffdc] must be even since this is done in pairs.
+
+; Return carry on success.
+
+	ld a, [hBGMapUpdate]
+	and a
+	ret z
+
+	ld a, [rVBK]
+	push af
+	ld [hSPBuffer], sp
+
+	ld hl, BGMapBufferPtrs
+	ld sp, hl
+
+; We can now pop the addresses of affected spots on the BG Map
+
+	ld hl, BGMapPalBuffer
+	ld de, BGMapBuffer
+
+
+.next
+; Copy a pair of 16x8 blocks (one 16x16 block)
+
+rept 2
+; Get our BG Map address
+	pop bc
+
+; Palettes
+	ld a, 1
+	ld [rVBK], a
+
+	ld a, [hli]
+	ld [bc], a
+	inc c
+	ld a, [hli]
+	ld [bc], a
+	dec c
+
+; Tiles
+	ld a, 0
+	ld [rVBK], a
+
+	ld a, [de]
+	inc de
+	ld [bc], a
+	inc c
+	ld a, [de]
+	inc de
+	ld [bc], a
+endr
+
+; We've done 2 16x8 blocks
+	ld a, [$ffdc]
+	dec a
+	dec a
+	ld [$ffdc], a
+
+	jr nz, .next
+
+
+	ld a, [hSPBuffer]
+	ld l, a
+	ld a, [hSPBuffer + 1]
+	ld h, a
+	ld sp, hl
+
+	pop af
+	ld [rVBK], a
+
+	xor a
+	ld [hBGMapUpdate], a
+	scf
+	ret
+; 163a
+
+
+WaitTop: ; 163a
+; Wait until the top third of the BG Map is being updated.
+
+	ld a, [hBGMapMode]
+	and a
+	ret z
+
+	ld a, [hBGMapThird]
+	and a
+	jr z, .done
+
+	call DelayFrame
+	jr WaitTop
+
+.done
+	xor a
+	ld [hBGMapMode], a
+	ret
+; 164c
+
+
+UpdateBGMap: ; 164c
+; Update the BG Map, in thirds, from TileMap and AttrMap.
+
+	ld a, [hBGMapMode]
+	and a
+	ret z
+
+; BG Map 0
+	dec a ; 1
+	jr z, .Tiles
+	dec a ; 2
+	jr z, .Attr
+
+; BG Map 1
+	dec a
+
+	ld a, [hBGMapAddress]
+	ld l, a
+	ld a, [hBGMapAddress + 1]
+	ld h, a
+	push hl
+
+	xor a
+	ld [hBGMapAddress], a
+	ld a, VBGMap1 >> 8
+	ld [hBGMapAddress + 1], a
+
+	ld a, [hBGMapMode]
+	push af
+	cp 3
+	call z, .Tiles
+	pop af
+	cp 4
+	call z, .Attr
+
+	pop hl
+	ld a, l
+	ld [hBGMapAddress], a
+	ld a, h
+	ld [hBGMapAddress + 1], a
+	ret
+
+
+.Attr
+	ld a, 1
+	ld [rVBK], a
+
+	ld hl, AttrMap
+	call .update
+
+	ld a, 0
+	ld [rVBK], a
+	ret
+
+
+.Tiles
+	ld hl, TileMap
+
+
+.update
+	ld [hSPBuffer], sp
+	
+; Which third?
+	ld a, [hBGMapThird]
+	and a ; 0
+	jr z, .top
+	dec a ; 1
+	jr z, .middle
+	; 2
+
+
+THIRD_HEIGHT EQU SCREEN_HEIGHT / 3
+
+
+.bottom
+	ld de, 2 * THIRD_HEIGHT * SCREEN_WIDTH
+	add hl, de
+	ld sp, hl
+
+	ld a, [hBGMapAddress + 1]
+	ld h, a
+	ld a, [hBGMapAddress]
+	ld l, a
+
+	ld de, 2 * THIRD_HEIGHT * BG_MAP_WIDTH
+	add hl, de
+
+; Next time: top third
+	xor a
+	jr .start
+
+
+.middle
+	ld de, THIRD_HEIGHT * SCREEN_WIDTH
+	add hl, de
+	ld sp, hl
+
+	ld a, [hBGMapAddress + 1]
+	ld h, a
+	ld a, [hBGMapAddress]
+	ld l, a
+
+	ld de, THIRD_HEIGHT * BG_MAP_WIDTH
+	add hl, de
+
+; Next time: bottom third
+	ld a, 2
+	jr .start
+
+
+.top
+	ld sp, hl
+
+	ld a, [hBGMapAddress + 1]
+	ld h, a
+	ld a, [hBGMapAddress]
+	ld l, a
+
+; Next time: middle third
+	ld a, 1
+
+
+.start
+; Which third to update next time
+	ld [hBGMapThird], a
+
+; Rows of tiles in a third
+	ld a, SCREEN_HEIGHT / 3
+
+; Discrepancy between TileMap and BGMap
+	ld bc, BG_MAP_WIDTH - (SCREEN_WIDTH - 1)
+
+
+.row
+; Copy a row of 20 tiles
+rept SCREEN_WIDTH / 2 - 1
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+endr
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+
+	add hl, bc
+	dec a
+	jr nz, .row
+
+
+	ld a, [hSPBuffer]
+	ld l, a
+	ld a, [hSPBuffer + 1]
+	ld h, a
+	ld sp, hl
+	ret
+; 170a
+
+
+Serve1bppRequest: ; 170a
+; Only call during the first fifth of VBlank
+
+	ld a, [Requested1bpp]
+	and a
+	ret z
+
+; Back out if we're too far into VBlank
+	ld a, [rLY]
+	cp 144
+	ret c
+	cp 146
+	ret nc
+
+; Copy [Requested1bpp] 1bpp tiles from [Requested1bppSource] to [Requested1bppDest]
+
+	ld [hSPBuffer], sp
+
+; Source
+	ld hl, Requested1bppSource
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	ld sp, hl
+	
+; Destination
+	ld hl, Requested1bppDest
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	
+; # tiles to copy
+	ld a, [Requested1bpp]
+	ld b, a
+
+	xor a
+	ld [Requested1bpp], a
+
+.next
+
+rept 3
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	ld [hl], d
+	inc l
+endr
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	ld [hl], d
+
+	inc hl
+	dec b
+	jr nz, .next
+
+
+	ld a, l
+	ld [Requested1bppDest], a
+	ld a, h
+	ld [Requested1bppDest + 1], a
+
+	ld [Requested1bppSource], sp
+
+	ld a, [hSPBuffer]
+	ld l, a
+	ld a, [hSPBuffer + 1]
+	ld h, a
+	ld sp, hl
+	ret
+; 1769
+
+
+Serve2bppRequest: ; 1769
+; Only call during the first fifth of VBlank
+
+	ld a, [Requested2bpp]
+	and a
+	ret z
+
+; Back out if we're too far into VBlank
+	ld a, [rLY]
+	cp 144
+	ret c
+	cp 146
+	ret nc
+	jr _Serve2bppRequest
+
+
+Serve2bppRequest@VBlank: ; 1778
+
+	ld a, [Requested2bpp]
+	and a
+	ret z
+
+_Serve2bppRequest: ; 177d
+; Copy [Requested2bpp] 2bpp tiles from [Requested2bppSource] to [Requested2bppDest]
+
+	ld [hSPBuffer], sp
+	
+; Source
+	ld hl, Requested2bppSource
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	ld sp, hl
+	
+; Destination
+	ld hl, Requested2bppDest
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	
+; # tiles to copy
+	ld a, [Requested2bpp]
+	ld b, a
+
+	xor a
+	ld [Requested2bpp], a
+	
+.next
+
+rept 7
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+endr
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+
+	inc hl
+	dec b
+	jr nz, .next
+
+
+	ld a, l
+	ld [Requested2bppDest], a
+	ld a, h
+	ld [Requested2bppDest + 1], a
+
+	ld [Requested2bppSource], sp
+
+	ld a, [hSPBuffer]
+	ld l, a
+	ld a, [hSPBuffer + 1]
+	ld h, a
+	ld sp, hl
+	ret
+; 17d3
+
+
+AnimateTileset: ; 17d3
+; Only call during the first fifth of VBlank
+
+	ld a, [$ffde]
+	and a
+	ret z
+	
+; Back out if we're too far into VBlank
+	ld a, [rLY]
+	cp 144
+	ret c
+	cp 151
+	ret nc
+
+	ld a, [hROMBank]
+	push af
+	ld a, BANK(_AnimateTileset)
+	rst Bankswitch
+
+	ld a, [rSVBK]
+	push af
+	ld a, 1
+	ld [rSVBK], a
+
+	ld a, [rVBK]
+	push af
+	ld a, 0
+	ld [rVBK], a
+
+	call _AnimateTileset
+
+	pop af
+	ld [rVBK], a
+	pop af
+	ld [rSVBK], a
+	pop af
+	rst Bankswitch
+	ret
+; 17ff
+
diff --git a/main.asm b/main.asm
index e78027753..51007a1bd 100644
--- a/main.asm
+++ b/main.asm
@@ -54,493 +54,7 @@ INCLUDE "engine/decompress.asm"
 INCLUDE "engine/palettes.asm"
 INCLUDE "engine/copy.asm"
 INCLUDE "engine/text.asm"
-
-
-DMATransfer: ; 15d8
-; Return carry if the transfer is completed.
-
-	ld a, [hDMATransfer]
-	and a
-	ret z
-
-; Start transfer
-	ld [rHDMA5], a
-
-; Execution is halted until the transfer is complete.
-
-	xor a
-	ld [hDMATransfer], a
-	scf
-	ret
-; 15e3
-
-
-UpdateBGMapBuffer: ; 15e3
-; Copy [$ffdc] 16x8 tiles from BGMapBuffer
-; to bg map addresses in BGMapBufferPtrs.
-
-; [$ffdc] must be even since this is done in pairs.
-
-; Return carry on success.
-
-	ld a, [hBGMapUpdate]
-	and a
-	ret z
-
-	ld a, [rVBK]
-	push af
-	ld [hSPBuffer], sp
-
-	ld hl, BGMapBufferPtrs
-	ld sp, hl
-
-; We can now pop the addresses of affected spots on the BG Map
-
-	ld hl, BGMapPalBuffer
-	ld de, BGMapBuffer
-
-
-.next
-; Copy a pair of 16x8 blocks (one 16x16 block)
-
-rept 2
-; Get our BG Map address
-	pop bc
-
-; Palettes
-	ld a, 1
-	ld [rVBK], a
-
-	ld a, [hli]
-	ld [bc], a
-	inc c
-	ld a, [hli]
-	ld [bc], a
-	dec c
-
-; Tiles
-	ld a, 0
-	ld [rVBK], a
-
-	ld a, [de]
-	inc de
-	ld [bc], a
-	inc c
-	ld a, [de]
-	inc de
-	ld [bc], a
-endr
-
-; We've done 2 16x8 blocks
-	ld a, [$ffdc]
-	dec a
-	dec a
-	ld [$ffdc], a
-
-	jr nz, .next
-
-
-	ld a, [hSPBuffer]
-	ld l, a
-	ld a, [hSPBuffer + 1]
-	ld h, a
-	ld sp, hl
-
-	pop af
-	ld [rVBK], a
-
-	xor a
-	ld [hBGMapUpdate], a
-	scf
-	ret
-; 163a
-
-
-WaitTop: ; 163a
-; Wait until the top third of the BG Map is being updated.
-
-	ld a, [hBGMapMode]
-	and a
-	ret z
-
-	ld a, [hBGMapThird]
-	and a
-	jr z, .done
-
-	call DelayFrame
-	jr WaitTop
-
-.done
-	xor a
-	ld [hBGMapMode], a
-	ret
-; 164c
-
-
-UpdateBGMap: ; 164c
-; Update the BG Map, in thirds, from TileMap and AttrMap.
-
-	ld a, [hBGMapMode]
-	and a
-	ret z
-
-; BG Map 0
-	dec a ; 1
-	jr z, .Tiles
-	dec a ; 2
-	jr z, .Attr
-
-; BG Map 1
-	dec a
-
-	ld a, [hBGMapAddress]
-	ld l, a
-	ld a, [hBGMapAddress + 1]
-	ld h, a
-	push hl
-
-	xor a
-	ld [hBGMapAddress], a
-	ld a, VBGMap1 >> 8
-	ld [hBGMapAddress + 1], a
-
-	ld a, [hBGMapMode]
-	push af
-	cp 3
-	call z, .Tiles
-	pop af
-	cp 4
-	call z, .Attr
-
-	pop hl
-	ld a, l
-	ld [hBGMapAddress], a
-	ld a, h
-	ld [hBGMapAddress + 1], a
-	ret
-
-
-.Attr
-	ld a, 1
-	ld [rVBK], a
-
-	ld hl, AttrMap
-	call .update
-
-	ld a, 0
-	ld [rVBK], a
-	ret
-
-
-.Tiles
-	ld hl, TileMap
-
-
-.update
-	ld [hSPBuffer], sp
-	
-; Which third?
-	ld a, [hBGMapThird]
-	and a ; 0
-	jr z, .top
-	dec a ; 1
-	jr z, .middle
-	; 2
-
-
-THIRD_HEIGHT EQU SCREEN_HEIGHT / 3
-
-
-.bottom
-	ld de, 2 * THIRD_HEIGHT * SCREEN_WIDTH
-	add hl, de
-	ld sp, hl
-
-	ld a, [hBGMapAddress + 1]
-	ld h, a
-	ld a, [hBGMapAddress]
-	ld l, a
-
-	ld de, 2 * THIRD_HEIGHT * BG_MAP_WIDTH
-	add hl, de
-
-; Next time: top third
-	xor a
-	jr .start
-
-
-.middle
-	ld de, THIRD_HEIGHT * SCREEN_WIDTH
-	add hl, de
-	ld sp, hl
-
-	ld a, [hBGMapAddress + 1]
-	ld h, a
-	ld a, [hBGMapAddress]
-	ld l, a
-
-	ld de, THIRD_HEIGHT * BG_MAP_WIDTH
-	add hl, de
-
-; Next time: bottom third
-	ld a, 2
-	jr .start
-
-
-.top
-	ld sp, hl
-
-	ld a, [hBGMapAddress + 1]
-	ld h, a
-	ld a, [hBGMapAddress]
-	ld l, a
-
-; Next time: middle third
-	ld a, 1
-
-
-.start
-; Which third to update next time
-	ld [hBGMapThird], a
-
-; Rows of tiles in a third
-	ld a, SCREEN_HEIGHT / 3
-
-; Discrepancy between TileMap and BGMap
-	ld bc, BG_MAP_WIDTH - (SCREEN_WIDTH - 1)
-
-
-.row
-; Copy a row of 20 tiles
-rept SCREEN_WIDTH / 2 - 1
-	pop de
-	ld [hl], e
-	inc l
-	ld [hl], d
-	inc l
-endr
-	pop de
-	ld [hl], e
-	inc l
-	ld [hl], d
-
-	add hl, bc
-	dec a
-	jr nz, .row
-
-
-	ld a, [hSPBuffer]
-	ld l, a
-	ld a, [hSPBuffer + 1]
-	ld h, a
-	ld sp, hl
-	ret
-; 170a
-
-
-Serve1bppRequest: ; 170a
-; Only call during the first fifth of VBlank
-
-	ld a, [Requested1bpp]
-	and a
-	ret z
-
-; Back out if we're too far into VBlank
-	ld a, [rLY]
-	cp 144
-	ret c
-	cp 146
-	ret nc
-
-; Copy [Requested1bpp] 1bpp tiles from [Requested1bppSource] to [Requested1bppDest]
-
-	ld [hSPBuffer], sp
-
-; Source
-	ld hl, Requested1bppSource
-	ld a, [hli]
-	ld h, [hl]
-	ld l, a
-	ld sp, hl
-	
-; Destination
-	ld hl, Requested1bppDest
-	ld a, [hli]
-	ld h, [hl]
-	ld l, a
-	
-; # tiles to copy
-	ld a, [Requested1bpp]
-	ld b, a
-
-	xor a
-	ld [Requested1bpp], a
-
-.next
-
-rept 3
-	pop de
-	ld [hl], e
-	inc l
-	ld [hl], e
-	inc l
-	ld [hl], d
-	inc l
-	ld [hl], d
-	inc l
-endr
-	pop de
-	ld [hl], e
-	inc l
-	ld [hl], e
-	inc l
-	ld [hl], d
-	inc l
-	ld [hl], d
-
-	inc hl
-	dec b
-	jr nz, .next
-
-
-	ld a, l
-	ld [Requested1bppDest], a
-	ld a, h
-	ld [Requested1bppDest + 1], a
-
-	ld [Requested1bppSource], sp
-
-	ld a, [hSPBuffer]
-	ld l, a
-	ld a, [hSPBuffer + 1]
-	ld h, a
-	ld sp, hl
-	ret
-; 1769
-
-
-Serve2bppRequest: ; 1769
-; Only call during the first fifth of VBlank
-
-	ld a, [Requested2bpp]
-	and a
-	ret z
-
-; Back out if we're too far into VBlank
-	ld a, [rLY]
-	cp 144
-	ret c
-	cp 146
-	ret nc
-	jr _Serve2bppRequest
-
-
-Serve2bppRequest@VBlank: ; 1778
-
-	ld a, [Requested2bpp]
-	and a
-	ret z
-
-_Serve2bppRequest: ; 177d
-; Copy [Requested2bpp] 2bpp tiles from [Requested2bppSource] to [Requested2bppDest]
-
-	ld [hSPBuffer], sp
-	
-; Source
-	ld hl, Requested2bppSource
-	ld a, [hli]
-	ld h, [hl]
-	ld l, a
-	ld sp, hl
-	
-; Destination
-	ld hl, Requested2bppDest
-	ld a, [hli]
-	ld h, [hl]
-	ld l, a
-	
-; # tiles to copy
-	ld a, [Requested2bpp]
-	ld b, a
-
-	xor a
-	ld [Requested2bpp], a
-	
-.next
-
-rept 7
-	pop de
-	ld [hl], e
-	inc l
-	ld [hl], d
-	inc l
-endr
-	pop de
-	ld [hl], e
-	inc l
-	ld [hl], d
-
-	inc hl
-	dec b
-	jr nz, .next
-
-
-	ld a, l
-	ld [Requested2bppDest], a
-	ld a, h
-	ld [Requested2bppDest + 1], a
-
-	ld [Requested2bppSource], sp
-
-	ld a, [hSPBuffer]
-	ld l, a
-	ld a, [hSPBuffer + 1]
-	ld h, a
-	ld sp, hl
-	ret
-; 17d3
-
-
-AnimateTileset: ; 17d3
-; Only call during the first fifth of VBlank
-
-	ld a, [$ffde]
-	and a
-	ret z
-	
-; Back out if we're too far into VBlank
-	ld a, [rLY]
-	cp 144
-	ret c
-	cp 151
-	ret nc
-
-	ld a, [hROMBank]
-	push af
-	ld a, BANK(_AnimateTileset)
-	rst Bankswitch
-
-	ld a, [rSVBK]
-	push af
-	ld a, 1
-	ld [rSVBK], a
-
-	ld a, [rVBK]
-	push af
-	ld a, 0
-	ld [rVBK], a
-
-	call _AnimateTileset
-
-	pop af
-	ld [rVBK], a
-	pop af
-	ld [rSVBK], a
-	pop af
-	rst Bankswitch
-	ret
-; 17ff
-
+INCLUDE "engine/video.asm"
 
 GetSpritePalette: ; 17ff
 	push hl