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Il Coder Sappharad (Paul Kratt) ci delizia con il rilascio di questa comoda utility che permette di creare delle immagini GDI "from scratch" ovvero da zero, dando in pasto al programma in questione direttamente i files di nostro interesse.
L'applicazione è disponibile per:
MAC OS X 10.7 or newer,
WINDOWS XP or newer
WINDOWS XP (COMMAND LINE) compatibile con Linux ed OSX attraverso il cross platform .NET framework "MONO".
Il codice sorgente è disponibile a questo indirizzo: http://github.com/Sappharad/GDIbuilder
GDIbuilder
Utility to assist with building Dreamcast .gdi images from scratch
When provided with a folder of data files, the IP.BIN bootsector, and optional raw CDDA tracks, this tool will automatically generate the data track(s) for the high density area of a GD-ROM image. It also generates the track TOC which is written into the bootsector.
A bootable GD-ROM requires the primary executable (usually called 1ST_READ.BIN) to be placed at the end of the final data track or it will not be loaded by the console. This requirement does not exist for MIL-CD's.
ISO9660 code was forked from .NET DiscUtils, with a number of modifications made:
When Joilet is disabled (which it is for this tool), don't output supplementary file tables
Reversed the order that DiscUtils outputs the ISO sections. (Directory Tables come before files now)
Fixed bug in non-joilet filename output. Filenames were not being appended with ;1 like they should be.
Added Start LBA offset for entire image
Added End LBA offset for entire image. Image will be padded to desired size.
Added End of last file LBA, if set all files will be pushed back in the image to this location.
Added properties to set most of the text identifiers (Application, Volume Set, Preparer, etc.)
Removed stuff not being used by this application, such as other image formats and filesystems.Technical Details
The primary executable on a Dreamcast GD-ROM (usually 1ST_READ.BIN) must be located at a specifc LBA sector for the disc to boot. The required sector is 549150 - 150 - 1ST_READ_SIZE, where 1ST_READ_SIZE is the number of sectors that 1ST_READ.BIN takes up on the disc. This tool was created to make it easier to generate images with the executable in the correct location. Additionally, when CDDA is used 150 empty sectors always separate the data and audio tracks on the disc. The tool also accounts for this when generating the data tracks. Finally, the IP.BIN bootsector contains a table of contents starting at offset 0x100. This TOC lists the tracks in the high-density area of the disc along with their LBA offset and track type. This information is written to the bootsector of the generated image.
The Gigabyte Disc Read Only Memory, or GD-ROM.
Many newcomers think that the Dreamcast used standard 700mb CD-ROM discs. This is incorrect. The Dreamcast actually used a format called the GD-ROM. This is a proprietary Sega format used only for the Dreamcast and some Sega arcade hardware (the NAOMI, NAOMI 2 and Triforce Board). GD-ROMs contain approximately 1.2gb of data split between two different sections. If you flip over a GD-ROM you'll notice that it's split into roughly 3 regions. The innermost region houses standard CD-ROM data that can be read in a computer. There's typically nothing of interest here (though some games contain bonus desktop images). There's another ring which, if looked at in the right light, contains Sega trademark information. The outer area of the disc is the high density region where the game data is stored. This cannot be read by a standard CD-ROM drive.
CDI Images
CDI images (for use with DiskJuggler and some other programs) are what you'll find the most to download here. These games have been ripped from GD-ROMs and prepared to fit a 70 minute 700mb CD-R (some CDIs are made for larger capacity discs, such as 99 minute discs). Thankfully most Dreamcast games did not make use of the full space of the GD-ROM, which means they can be essentially 1:1 images of the GD-ROM. Some games must be downsampled (by reducing the quality of audio or video aspects) to fit onto a 700mb disc. If you are using an actual Dreamcast, you want CDI images. They are ready to be burned and played. CDI images can also be played in an emulator, however they are not ideal since some downsampling may have occurred.
GDI Images
This is a dump of the actual GDI containing all original data. These can only be used in an emulator; they cannot be burned unless you rip the data and prepare the game to selfboot on a Dreamcast. If you are using an emulator, GDIs are your ideal choice since they are a 1:1 copy of the original game. At the time of writing, the GDI section at the ISO Zone is slim pickings, but fatman01923 and myself (comradesnarky) will be working to expand the section with TOSEC verified GD-ROM dumps. The GDI set for Dreamcast is also far from complete; at times, you may have no choice but to use a CDI image.
Utility molto comoda se si è ad esempio tra i fortunati possessori dell'USB GDROM Controller by Mnemo che supporta unicamente (al momento) il formato .GDI
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Originariamente Scritto da Sk8er000
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