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fastbilly1
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Re: How is your Dreamcast gaming going on?

by fastbilly1 Tue Feb 21, 2017 11:31 am

RCBH928 wrote:Last I heard Dreamcast and later generation consoles emulation has not been perfected. Meaning with the last dying Dreamcast, we will lose the option of playing Dreamcast games. This means we will lose a piece of gaming history and future generations will hear about Dreamcast games (or later!) but will not be able to experience them (unlike video and audio that can transfer to other mediums).

You are decades away from there being no functioning Dreamcasts. And by that time Dreamcast emulation will be at the point that NES emulation is now. Dreamcast emulation is by no means bad currently, but there are still titles that do not work, just like any post 4thgen console.
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Re: How is your Dreamcast gaming going on?

by marurun Tue Feb 21, 2017 11:42 am

RCBH928 wrote:But the Dreamcast is not a CD-R drive its a GD-ROM drive. Can that affect the system's lifespan?


Actually, everything I've read suggests that the Dreamcast's GD-ROM drive is actually a standard Yamaha CD drive with custom firmware. The GD-ROM specification uses the exact same laser as a CD-ROM, but the disc is deliberately spun more slowly to that the laser can pick out the smaller pits. So basically, the Dreamcast uses a high-speed CD drive deliberately run at a slower speed. But that probably means that when reading GD-ROM discs it has a harder time seeking non-consecutive data. It may actually be that using CD media, even CD-R media, in a Dreamcast could be easier on the drive than the native GD-ROM media. Unless you have one of those later models where the firmware disallows reading traditional CD media. Although, I have yet to meet or hear from anyone who actually owns a Dreamcast that won't read regular CDs, so those might just be rumor.
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Re: How is your Dreamcast gaming going on?

by Tanooki Tue Feb 21, 2017 12:18 pm

Ok for starters he's right above, the DC uses a stock CD drive but a custom firmware.

Read up on this for what a GD-ROM is: https://en.wikipedia.org/wiki/GD-ROM

Basically better compressed set of pits allows 25% more data storage over your largest industry stock CDs (so 1.2GB.)

Might as well read the few lines on MIL-CD while you're at it since this was the back door for pirates: https://en.wikipedia.org/wiki/MIL-CD

And here's the tech info piece from the GDROM wiki entry:

The GD-ROM in the Dreamcast works in constant angular velocity (CAV) mode, like the majority of modern optical drives. Very old CD-ROM drives read with a constant linear velocity (CLV) design, however (usually 12x or slower). Sega achieved the higher density by decreasing the speed of the disc to half and by letting the standard CD-ROM components read at the normal rate thus nearly doubling the disc's data density. This method allowed Sega to use cheaper off-the-shelf components when building the Dreamcast.

The NetBSD project has developed a GDRom driver for NetBSD. A port of that driver for Linux exists, though due to licensing issues and the poor compatibility of that driver with Linux kernel interfaces, a new Linux driver is under development.

Linux kernel 2.6.25 comes with support for the GD-ROM drive on the Dreamcast.

...stock drive, custom firmware, has been figured out and drivers have been made for it going way back but you need a compatible drive that can take that custom driver. If you do, you can read the entire disc and do as you please, otherwise you're stuck with a tiny CD area on the disc where it warns you it's meant verbally for Sega Dreamcast and then the mass rest of the disc is hiding under the shroud.



Oh and Dreamcast emulation, using demul's latest appears I'd think around 80-90% complete, some games have breaking errors but most stuff is minor and most stuff runs fantastic. I wouldn't feel too bad if you went that route as it works.
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Re: How is your Dreamcast gaming going on?

by Sarge Tue Feb 21, 2017 12:34 pm

I haven't played much with Dreamcast emulation, but what do you figure it's at? N64 level?

Thanks for the post, Tanooki, that's fascinating stuff. It makes perfect sense from an engineering perspective, too! Pretty creative, actually.
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Re: How is your Dreamcast gaming going on?

by marurun Tue Feb 21, 2017 2:53 pm

According to some of what I've read, you can actually coax a standard CD/DVD drive to do linear reads of Dreamcast data without any firmware changes. The problem is when you need to seek. The drive gets the math completely wrong because of the increased data density. But the GD-ROM format is an extremely conservative method of packing extra data into a disc and use bog-standard hardware to read it. Sega and Yamaha were both thinking with $ in mind with this tech. How can we keep it cheap, cheap, cheap.
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Re: How is your Dreamcast gaming going on?

by CRTGAMER Tue Feb 21, 2017 2:57 pm

marurun wrote:According to some of what I've read, you can actually coax a standard CD/DVD drive to do linear reads of Dreamcast data without any firmware changes. The problem is when you need to seek. The drive gets the math completely wrong because of the increased data density. But the GD-ROM format is an extremely conservative method of packing extra data into a disc and use bog-standard hardware to read it. Sega and Yamaha were both thinking with $ in mind with this tech. How can we keep it cheap, cheap, cheap.

NO. Read is out to in vs in to out.
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Re: How is your Dreamcast gaming going on?

by marurun Tue Feb 21, 2017 3:18 pm

CRTGAMER wrote:
marurun wrote:According to some of what I've read, you can actually coax a standard CD/DVD drive to do linear reads of Dreamcast data without any firmware changes. The problem is when you need to seek. The drive gets the math completely wrong because of the increased data density. But the GD-ROM format is an extremely conservative method of packing extra data into a disc and use bog-standard hardware to read it. Sega and Yamaha were both thinking with $ in mind with this tech. How can we keep it cheap, cheap, cheap.

NO. Read is out to in vs in to out.


One, I have no idea what you're talking about. Use more clear language.

Two, I can play that game, also.

NO. You're wrong.
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Re: How is your Dreamcast gaming going on?

by Sarge Tue Feb 21, 2017 3:44 pm

I'm not sure what you mean by out-to-in vs. in-to-out, either. I'd greatly appreciate some clarification!

Either way, I'm learning a lot, just from reading and discussing and looking up stuff on these things. The travails of a computer engineering background. :)
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Re: How is your Dreamcast gaming going on?

by CRTGAMER Tue Feb 21, 2017 4:36 pm

GD-ROM reads outer track to inner track, opposite of regular disc readers. Posted an elaboration of this and how different sized discs will have different pit sizes which do affect how a laser needs to adjust how it reads in the Pressed vs CD-R Guide.
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Re: How is your Dreamcast gaming going on?

by Sarge Tue Feb 21, 2017 4:58 pm

I can't confirm that things were written from outside-to-inside. You wouldn't have a link to that, would you? I'd love to read about it!

I know that the same was rumored about Gamecube discs, but it isn't true. I also know that there were CD-based games released on Dreamcast, like Tony Hawk's Pro Skater, which worked swimmingly in a PC, including reading all the file system data.
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