The Mike Tyson´s Punch-Out

Caution: You do not need to understand the meaning of this section to have fun playing Punch-Out!!
It is intented solely for PO!! maniacs that want to know every byte of the game

The Mike Tyson´s Punch-Out!! rom in detail

Cartridges:

	Circuit Board	prg-chip	chr-chip	MMC	security chip
MTPO-PAL	NES-PNROM-03 c1987 Nintendo	PAL-PT-1 PRG MN231001NXU 885B3	NES-PT-O CHR MN231003NXG 88152	Nintendo MMC2-L S 8814A	3195A c1986 Nintendo 8829A
PO!!-PAL	c1987 Nintendo NES-PNROM-05	PAL-QP-O PRG LH230676 9103 E	NES-QP-O CHR LH2311L7 9049 D	Nintendo MMC2-L S 9104 AA	3195A c1986 Nintendo 9104 A
MTPO-NTSC	NES-PEEOROM-01 c1987 Nintendo	NES-PT-O PRG MN231001NXH 7N6BT	NES-PT-O CHR MN231003NXG 7N050	RD387-001 c1987 Nintendo 7N0	6113 c1987 Nintendo 8743 C
PO!!-NTSC	c1987 Nintendo NES-PNROM-05	NES-QP-O PRG MN231001NUY 077B3	NES-QP-O CHR MN231003NUZ 06752	MMC2 RD387-001 c1987 Nintendo07.0	6113B1 c1988 9031 3AA
MTPO-Famicom	to come...
		c = the copyright symbol

ROMS:
Both roms, the MTPO and the PO!! rom files have got the same overall size. They are 262160 bytes large.

The rom is devided in three major sections (use a hexeditor like Hex Workshop):
Header (size: 16 bytes, Byte 1-16, Offset 00000-00010)
PRG data (size: 131072 bytes, Byte 17-131088, Offset 00011-20010)
CHR data (size 131072 bytes, Byte 131089-262160, Offset 20011-40010)

Header

The first 16 bytes of the Punch-Out.nes rom are added by the person who made the rom out of the cartridge. It is used to indicate the emulator what sort of cartridge is following.
In hex the Punch-Out!! header looks like this:
first line is the MTPO.nes, second line is PO.nes

ROM	Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6	Byte 7	Byte 8	Byte 9	Byte 10	Byte 11	Byte 12	Byte 13	Byte 14	Byte 15	Byte 16
MTPO	4E	45	53	1A	08	10	90	00	00	00	00	00	00	4D	4A	52
PO!!	4E	45	53	1A	08	10	99	00	00	00	00	00	00	00	00	00
	N	E	S	Character Break	PRG (Hex number depends on size of PRG file)	CHR (Hex number depends on size of CHR file)								??	??	??

Byte 1-4 are standard bytes, the emulator needs to detect that this is a NES cartridge rom file.
Byte 5-6 indicate the emulator how mamy pages of programm and character data the cartridge contains.
Byte 7:
The first digit is 9 and stands for the mapper #9. It stands for the MMC2 chip
The second digit stores some cartridge information for the emulator.
0 = H (Horizontal Mirroring ONLY)
9 = V + 4scr. (Vertical Mirroring + 4 Screen VRAM ON)

PRG data

The first of the two main parts of the Punch-Out!! rom file is the so called prg part. "PRG" stands for "programm". The prg part contains that information that is stored on the cartridge in the ROM chip (ROM=PRG).

This part is the most relevant in order to make a game working.

The size of the prg part is 131072 bytes. This indicates that the information is stored in 8 x 16kb pages (8 x 16384 = 131072)

So in the header Byte no.5 is 08 because Punch-Out!! has got 8 programm pages (each 16kb)

The prg data is stored between Byte 17-131088, Offset 00011-20010)

prg. page	start offset	end offset
1	00011	04010
2	04011	08010
3	08011	0C010
4	0C011	10010
5	10011	14010
6	14011	18010
7	18011	1C010
8	1C011	20010

Compared with the punchout.nsf audio ripp, I konw that major parts are the same to parts of the rom:

00080-02000(.nsf file)=10010-11F90 (rom file)
02070-08080(.nsf file)=1A000-20010 (rom file). So all the Punch-Out!! music is stored in parts of prg.page 5,7 and 8

Aditionally the nsf header provides these information:
load adress: 0080
init adress: 809F
play adress: 0080
-still not sure how to use those infos...

CHR data

The other main part of the rom is the chr section. In this part all the graphics are stored. "CHR" stands for "Characters". The chr part is the takeout of the VROM Chip of the cartridge. In Punch-Out!! the CHR data size is 131072 bytes. This indicates that the graphics in this rom are stored in 16 pages (each 8kb of size). NEW: I think Punch-Out!! uses 32 pages (each4kb!) When we do the math we see: 131072 bytes:16 = 8192bytes. In hex numbers 16 is 10. So the 6^th header byte is 10 to indicate that the rom has got 16 graphic (character) pages. mtpo-chr data begins at Byte 131088 and ends at the end of the rom at Byte 262160. Offset is 20010-40010. (VROM=CHR)

Each character page consists of 16x32=512 tiles. So the Punch-Out!! rom consists of 512x16=8192 tiles. With 8192 bytes per character page and 512 tiles per page we get a result of 16 bytes for the size of each tile.
Additionally each tile is 8x8 pixels large.

Now to the 16 pages of chr graphics: Each page consist of 32x16 tiles as you can see: (remember: 1 page = 512 tiles)

The following pics show the 16 pages of MTPO. When you move with your mouse over then they change to the PO!! equivalent, so you can see, which tiles of the different chr pages are different from version to version (e.g. try page 3!)