Difference between revisions of "Boot.dat"
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For instance, the entry for file 0001 is 4E 01 00 F7. To find the starting location of this file in a CD image, we first reverse the first 2.5 bytes (yielding 0x0014e) then multiply the result by 2048 for an ISO image (= 0xa7000) or by 2354 for a BIN (= 0xbff3c, then add an additional 24 to account for the sector header, giving a final total of 0xbff54). | For instance, the entry for file 0001 is 4E 01 00 F7. To find the starting location of this file in a CD image, we first reverse the first 2.5 bytes (yielding 0x0014e) then multiply the result by 2048 for an ISO image (= 0xa7000) or by 2354 for a BIN (= 0xbff3c, then add an additional 24 to account for the sector header, giving a final total of 0xbff54). | ||
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| + | [[Image:Chrono_Cross_Internal_Boot_Menu.png]] | ||
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| + | [[Image:Chrono_Cross_Internal_Boot_Menu_US_Retail.png]] | ||
''From'': [[Chrono Cross File Structure]] | ''From'': [[Chrono Cross File Structure]] | ||
Latest revision as of 06:04, 7 September 2020
General Information
Chrono Cross
[Information compiled from several sources]
This file contains the first 38 sectors on the CD, and can be subdivided into several sections. The first 16 sectors (0-15) follow a pattern common to all PSX games; the remainder appear to have been concocted by Square especially for Chrono Cross.
- Sectors 0-3 are empty on the NA ~CDs, but may contain some form of identification data on the JP ~CDs.
- Sector 4 contains the string "Licensed by Squaresoft", which is displayed briefly on the screen as the game boots.
- Sectors 5-11 should contain the Playstation logo displayed on bootup, in .tmd format
- Sectors 12-15 are completely blank, including EDC/ECC data.
- Sector 16 contains unknown data, including some text.
- Sector 17 is mostly empty, but begins with an FF byte followed by "~CD001" (on both NA ~CDs)
- Sectors 18-19 are both empty except for 8 bytes of data at the beginning: 01 00 16 00 00 00 01 00
- Sectors 20-21 are also mostly empty and both begin with 01 00 00 00 00 16 00 01
- Sector 22 may contain the nearly empty TOC that's visible when mounting the CD in a standard manner
- Sector 23 is near-empty (02 00 02 00 17 00 2C 00 18 00 E0 60 25 00 22 00, 16 0-bytes, "CHRONOCROSS")
- Sectors 24-36 contain the real CD TOC, on which more below
- Sector 37 is another near-empty mystery, containing 34 non-zero bytes.
TOC
The Table of Contents (hereafter TOC) is literally the most important file to work with for purposes of Chrono Cross modification. It is essentially a giant pointer table that the game engine uses to determine where every file begins and ends, and occupies 12 sectors beginning at sector 24 (offset 0xc000 in an ISO, offset 0xdcc8 in a BIN).
The TOC entries have a four byte stride and can be presented thus:
SS SS FS BB
Where...
- S = "Logical Sector"; 2.5-byte little-endian pointer indicating the sector boundary on which the file begins.
- F = "Flag"; the first bit of this nybble will be set if and only if this TOC entry is a duplicate of the next real record.
- BB = Number of zeroed buffer bytes between the end of the file and the next sector boundary, divided by 8.
For instance, the entry for file 0001 is 4E 01 00 F7. To find the starting location of this file in a CD image, we first reverse the first 2.5 bytes (yielding 0x0014e) then multiply the result by 2048 for an ISO image (= 0xa7000) or by 2354 for a BIN (= 0xbff3c, then add an additional 24 to account for the sector header, giving a final total of 0xbff54).
