GD-Rom Dumping Guide (Old)

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Revision as of 19:46, 16 September 2013

Introduction

The GD-ROM format is actually a special and customized, multisession CD format developed by Yamaha for Sega. The Dreamcast console contained a modified 12x CD-ROM reader to read the format, which contained a high-density layer. This high-density zone is very similar to normal CD data, except that it is more squeezed (like a CD-R burned with the GigaRec technology by certain real Plextor writers). The high-density zone of GD-ROM contains subcodes and raw data sectors (2352 bytes per sector), and can even can contain CDDA audio tracks.

A GD-ROM consists of two zones:

• A low density area (the first 2 tracks)
• A high density area (the rest of the disc).

The low denisty area can be accessed by just about any drive, while the high density portion is only accessible by COMPATIBLE drives using a technique called "hotswapping." Hotswapping basically involves pressing the escape/eject button on the drive while in use to eject-and-switch-discs ("hot swap") so that the high density portion can be reached by the ripping software.

Since the low density area is visible by just about any drive, it can be dumped in the normal way (without hotswapping). See the Main CD Dumping Guide for instructions on how to dump the low density tracks.

Because only a handful of drives are capable of reading the high-density area of a GD-ROM disc there is an on-going list of SUPPORTED or UNSUPPORTED drives are provided below. The list is a work-in-progress, so please let us know if a drive can be added to either section! :)

Lastly, there are presently two methods used to dump redump.org GD-ROMs. This guide will attempt to walk you through each method. You are free to choose whichever seems the simplest!

Method A

Software needed

• CDRWin (v4.0a - v4.0h)
• dctools
• Audio trap disc

Instructions

The high density area (sector 45000-549150) can be dumped as follows:

1. Insert the audio trap disc (a disc with a hacked TOC of 99 mins audio, burn it with CloneCD or Alcohol).
2. Use 'startstop.exe [driveletter] 1' to stop the drive motor.
3. Use a pin to press the escape eject button, so the tray will eject (or remove the drive cover).
4. Insert the GD-ROM into the tray and gently push the tray back into the drive (or replace the drive cover if you removed it).
5. Now extract sectors 44990 - 549150 using CDRWin's 'Select Sectors' feature. Make sure you use the following settings:
   • CD Audio (2352)
   • File Format = INTEL
   • Error Recovery = Abort
   • Audio Speed = 1x
   • Read Retry Count = 1
6. Once the software is finished extracting, use 'ICE.exe dumpfile.bin 45000' to descramble and split the dump data.
7. If everything went well, the dump should be ready for submission!

Method B

Software needed

• DCdumper (v0.42a)
• CDRWin (v4.0a - v4.0h)
• dctools
• Audio trap disc

Instructions

The downside to Method A is that CDRWin (by itself) can have problems dumping certain sectors of the GD-ROM. Therefore, JamJam created a tool called 'DCdumper' to provide more secure sector verification during dumping that generally results in far less errors and more accurate dumps. CDRWin is still needed to align the laser, but DCdumper performs the actual dumping.

1. Insert the audio trap disc into the drive.
2. Open CDRWin and set it up like you would if you were using it to do the dump.
3. Change the 'Start-End' sector to 50000; leave everything else the same.
4. Next, use 'startstop.exe [driveletter] 1' to stop the drive motor.
5. Once the drive has stopped, carefully remove the trap disc using the hotswap technique (see above), and replace it with the GD-ROM.
   • IMPORTANT: To prevent damage to the edging of your disc, push the tray carefully and gently until it's 99.9% of the way in and won't seem to go any further. Then, give the WHOLE tray surface an EXTRA-HARD push. If you're lucky, you'll hear the magnet picking up the disc...but don't worry if you don't. As long as you pressed in really hard, nothing should happen to the GD-ROM...hopefully! :)
6. With the GD-ROM now successfully swapped, use CDRWin to pre-align the laser by entering the sector ranges you wish to dump and press 'Start'. Let it reach 1%, wait a few seconds longer, and then 'Cancel' the reading. This effectively "aligns" the laser for the next step.
7. Once the laser has been aligned you can run DCdumper to dump the same sector range: 'DCdumper.exe [driveletter] -df -dt'
8. Once you finish dumping all sections (1-49), a file called "dense.bin" will be created containing the scrambled dump data.
9. Extract the data using 'ICE.exe' from the dctools collection.
10. If everything went well, the dump is now ready for submission!

For more information on dumping GD-ROMs using METHOD B, see the DCdumper Tutorial.

Best Practices / Tips

• Burn the Audio Trap Disc image to a CD-RW vs. a regular CD-R. CD-RWs are more durable, and are less prone to damage than a CD-R.
• Hotswapping (the eject-pin-hole method) works very well, and is generally favored over the lid-removal method. However, extra care is necessary during the transition in order to avoid scratching the GD-ROM and/or audio trap disc.
• To prevent damage to the edging of your disc, push the GD-ROM in the tray carefully and gently until it's 99.9% of the way in and won't seem to go any further. Then, give ALL parts of the tray an EXTRA-HARD push. If you're lucky, you'll hear the magnet picing up the disc...but don't worry if you don't. As long as you pressed in really hard, nothing should happen to the GD-ROM...hopefully! :)
• If you own a Plextor drive, you can quickly determine the factory write offset value by using px_d8 (v1.01A). Usage: 'px_d8 [driveletter] 45000'. (Refer to the Main CD Dumping Guide for details on how to manually determine the write offset value.)
• A best-practice for dumping with DCdumper is to dump-then-match the GD-ROM in three separate section ranges. This technique allows you to quickly re-align the laser (using CDRWin), reset the trap disc, and resume dumping if/when DCdumper encounters an unreadable sector (which happens occasionally). The following is a recommended (though optional) range split to use for dumping: (1) 044990-240480 [sections 1-19], (2) 240481-435971 [sections 20-38], (3) 435972-549150 [sections 39-49]. DCdumper won't create a dense.bin until it has successfully matched all section dumps, so you can stop/restart the program at any point in time to pause dumping, realign the laser, or reset the audio trap disc.

Troubleshooting

• If you have a drive on the SUPPORTED list, and it doesn't work after some retries: (1) read ahead a bit (sector 60,000-x), (2) try/retry the normal range again, and (3) try removing the cover.
• If DCdumper is working fine and then begins to fail reading sector ranges, STOP the program, DELETE the failed partial .bin file(s) (since DCdumper does *NOT* do this for you), re-scan the opening 1-2% of the sector range using CDRWin, and then try re-running DCdumper to see if it fixes itself. If it still fails, you may need to re-insert the audio trap disc and realign the laser using CDRWin (i.e. start over). If it STILL fails, then you may have a bad disc or a drive-related problem. Check and/or clean your disc's data surface, and verify that your drive's firmware version is up-to-date.
• If you keep getting errors during the extraction OR if your drive fails to read the GD-ROM disc after swapping, then this most likely means that your drive isn't suitable for dumping GD-ROM discs. See the SUPPORTED and UNSUPPORTED lists for more information.
• If some of the required software tools aren't working properly, try updating your drive's firmware to the latest version. Out-of-date firmware has been known to cause problems with some of the homebrew tools used in dumping discs.

Supported Drives

Drives that have been tested and verified as COMPATIBLE.

• Lite-On LH-18A1H (themabus)
• Lite-On SOHD-167T (iR0b0t, Jackal)
• Plextor PX-W4824TA (pablogm123)
• Samsung TSSTCorp SH-D162C (tossEAC)
• Samsung TSSTCorp SH-D162D (iR0b0t, Jackal, tossEAC, r09, Rocknroms, nrl_quaker)

Reported Drives

Drives that have been reported as COMPATIBLE (unverified):

• LG GCR-8522B
• Lite-On LTD-165H
• Lite-On SOHD-16P9S
• NEC CDR-1901A
• Plextor PX-708A
• Plextor PX-755SA
• Plextor PX-W4824TU
• Samsung TSSTCorp TS-H192C
• Samsung TSSTCorp TS-H352C
• Samsung TSSTCorp TS-H353A
• Samsung TSSTCorp TS-H353B

Unsupported Drives

Drives that have been verified as being INCOMPATIBLE:

• ASUS CRW-5224A (axisleon)
• ASUS DRW-24B1ST a (Enker)
• LG BD-RE GGW-H20L (Teancum)
• LG CED-8120B (iR0b0t)
• LG GCC4482B (Enker)
• LG GDR-8164B (iR0b0t, Rocknroms)
• LG GSA-H10N (Enker)
• LG GSA-H42L (iR0b0t)
• Lite-On iHAS324-32 B (axisleon)
• Lite-On iHBS112 2 (Enker)
• Lite-On iHDP118 4 (Enker)
• Pioneer DVR-103 (iR0b0t)
• Pioneer DVD-129P (axisleon)
• Pioneer DVR-111 (axisleon)
• Pioneer DVR-216 (axisleon)
• Plextor PX-116A (axisleon)
• Plextor PX-760A (iR0b0t, Rocknroms, Jackal)
• Toshiba SD-M1502 (iR0b0t)
• SONY CRX140S (axisleon)
• SONY CRX230E (nrl_quaker)
• NEC ND-4550A (nrl_quaker)
• TEAC CD-532S (axisleon)
• Toshiba SD-M1502 (iR0b0t)
• TSSTcorp SH-S202J (nrl_quaker)
• HL-DT-ST BD-RE GGW-H20L (Teancum)

Forum

For any questions, suggestions or problems please visit the Dreamcast GD-ROM dumping topic in the forum. If you have anything to add to the dumping method or supported drives please share with us your findings.