ROM Header: Difference between revisions

 

{| class="wikitable"

!Offset

!Size

 

 

 

 

These fields could be tuned in replica cartridges to adapt to the actual maximum physical speed that the ROM can be accessed, but please pay attention that many emulators expect to find the 4 "standard" values here and actually use them as a "fixed ID" to detect if the ROM dump was byte-swapped.

|-

|0x04

|0x4

|Clock Rate

 

 

 

 

|-

|0x08

|0x4

|Boot Address

 

 

|Revision version of libultra, as ASCII letter.

|}

 

 

|0x10

|0x8

|64-bit check code calculated on 1 Mbyte of ROM contents starting from offset 0x1000 (after IPL3). This check code is computed with a custom algorithm implemented by IPL3 that verifies the integrity of the ROM before booting it. If the check code doesn't match, IPL3 refuses to boot the ROM and hangs the console.

 

 

 

 

 

 

 

 

|0x3B

|0x4

|The game code is 4 ASCII characters that are split up into 3 parts - the category code, the unique code and the destination code.

{| class="wikitable"

|0x0

|0x1

|An alphanumeric character that specifies the kind of media the game is stored on.

{| class="wikitable"

|-

!D

|-

!C

|-

!E

|-

!Z

|0x1

|0x2

|Two alphanumeric characters that identify the game.

|-

|0x3

|0x1

|An alphanumeric character that specifies the destination the game is intended for.

{| class="wikitable"

|+

|

|

|-

|

|

|-

|

|

|-

|

|

|-

|

|

|-

|

|

|-

|

|}

|}

|0xFC0

|IPL3

|}

 

The Advanced Homebrew ROM Header format is a convention that has been agreed upon in the N64 homebrew community to add additional information in the header, using unused fields. The goal of this convention is to let homebrew ROMs declare the correct saveype and controllers that are expected to play the game. The format has been introduced by the EverDrive 64 flashcard and has been later enhanced by the homebrew community.

 

Instead, by using the Advanced Hombrew ROM Header, emulators can automatically configure the required emulated hardware as expected without having to keep any additional database, by simply decoding specific fields of the ROM header. In addition to emulators, also development flashcarts and loaders can use this format to automatically configure the correct savetype when the ROM is loaded.

 

{| class="wikitable"

!Offset

|1

|Controller 1

Values 0x01-0x7F indicate a standard N64 controller, possibly with some installed pak.

 

|N64 controller with Controller Pak

!0x82

|-

!0x03

|-

!0xFF

!0x84

|Gamecube keyboard

|1

|Controller 2

|-

|0x36

|1

|Controller 3

|-

|0x37

|1

|Controller 4

|-

|0x3C

|2

|Game ID

|-

|0x3F

|}

 

Emulators not listed here do not support the advanced homebrew ROM header format.

{| class="wikitable"

|+

!Emulator

|-

|Ares

|-

|cen64

|}

 

Support by flashcarts can vary depending on the USB loader being used and/or the flashcart operating system. Notice that flashcarts can emulate a specific savetype but have nothing to do with controllers, so the maximum expected support is related to savetype.

{| class="wikitable"

|-

| rowspan="4" |64drive

|None

|-

|None

|-

|-

|UNFLoader

|-

| rowspan="3" |Everdrive 64

|-

|UNFLoader

|}