IP.BIN
Basic Overview
- Loaded and ran from Disc (GD-ROM, CD-ROM)
- Contains basic meta information for a disc
- Draws the Sega License Screen
- Possibly holds an MR Image
- Has space to run Code that is typically used in setting up the basic hardware then launching the binary on disc
General Header Information
Overview of Each piece of the IP.BIN listing file offset and memory location when loaded [1]
| Offset | Size | Load address | Contents |
|---|---|---|---|
| 0x0000-00FF | 0x00FF : 256 Bytes | 8C008000-8C0080FF | Meta information |
| 0x0100-02FF | 0x01FF : 512 Bytes | 8C008100-8C0082FF | Table of contents |
| 0x0300-36FF | 0x33FF : 13312 Bytes | 8C008300-8C00B6FF | SEGA license screen code |
| 0x3700-37FF | 0x00FF : 256 Bytes | 8C00B700-8C00B7FF | Area protection symbols |
| 0x3800-5FFF | 0x47FF : 18432 Bytes | 8C00B800-8C00DFFF | Bootstrap 1 |
| 0x6000-7FFF | 8C00E000-8C00FFFF | Bootstrap 2 (Not Required #Bootstraps) |
Execution Flow Overview
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Deeper Look into User Code
All IP.BIN files from Sega are generally made with the IP Maker software and follow the same basic layout codewise. Bootstrap 1 is very small and is responsible for setting some minor hardware registers then jumps immediately to Bootstrap 2. This second Bootstrap actually does the bulk of the work and handles setting up the stack, VBR, disables cpu caching and then handles the jump to 1ST_READ.BIN which is loaded to address 0x8C010000.
Bootstraps
This is the area in the IP.BIN that is completely unregulated and can be used however someone would like.
Bootstrap 1
This piece of code is generally very small, under 32 bytes and sets hardware registers.
- a custom MR Image can also live within this section at offset 0x3820, Address 0x8C00B820 and will be displayed on the license screen.
Bootstrap 2
This is Generally where all the base setup code is kept so our binary has a known, and clean execution environment in which it starts. In Warez releases this is the area that is responsible for a very sneaky trick. The 1ST_READ.BIN binary is kept as is on the disc, but then when scramble loaded by the bios (See Dreamcast_Boot_Process for further)) it will be unusable, so code was written to unscramble, the now ruined binary, in-place. The second part of this trick also reinitializes the GD-ROM drive and passes the HOLLY bios check so that the game may access the data on the disc and execute normally.
Other uses
- neoIP is a complete open source replacement for these bootstraps and is currently able to load: homebrew, official Katana and WINCE binaries from either a GD-ROM or CD-ROM developed by HaydenKow
- IP.BIN Replacement This as far as I know is the first LEGAL ip.bin replacement for the dc, however it is pretty much untested. Developed by LiENUS