Super gameboy color?

Discussion of programming and development for the original Game Boy and Game Boy Color.
tepples
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Re: Super gameboy color?

Post by tepples » Fri Nov 06, 2015 5:38 pm

The differences between standard DVD format and GameCube/Wii disc format are six "pinholes" in the lead-in, whose location is encoded in the Burst Cutting Area, and a modification of the parameters used for sector whitening. Wii also has 3% of disc space used by sector hashes.

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tokumaru
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Re: Super gameboy color?

Post by tokumaru » Fri Nov 06, 2015 6:36 pm

Espozo wrote:I guess if you do burn a DVD, you can't overwrite the data in any way, in that whatever is burned onto the DVD is permanent?
The basic idea behind reading optical media is that a laser is fired at the disc, and depending on whether the laser reflects back, that part of the disc is considered a 1 or a 0. Retail discs are pressed from a master (they're not burned at all), and contain pits that deflect the laser away from the reading sensor. Recordable discs are in fact burned, and the burned spots become opaque and stop reflecting the laser, so these spots have the same effect as the pits in a pressed disc, as far as the reader is concerned. Rewritable media is more complex, it's made of a material that can change states multiple times.
tokumaru wrote:Is this mini DVD-R technology different than what the GameCube normally uses?
Physically, the difference is that GameCube discs are pressed, and DVD-R is burned. In addition to that, there appears to be differences in the protocol, according to the page tepples linked to. I do know that the protection can be circumvented though, because there are people running games off of mini DVD-Rs.

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Drew Sebastino
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Re: Super gameboy color?

Post by Drew Sebastino » Fri Nov 06, 2015 7:12 pm

tokumaru wrote:The basic idea behind reading optical media is that a laser is fired at the disc, and depending on whether the laser reflects back, that part of the disc is considered a 1 or a 0.
It almost seems like a miracle that they are that reliable in that regard. I've never quite understood as to how programs never catastrophically fail from reading off of something as seemingly unreliable as that. (Just one bit could mean either jumping back to the start of a loop or running off into nowhere...)

Like you said though, the fact that if it's pressed or burned is irrelevant, so it all comes down to this protocol thing. If you bought new DVD to be burned, would the area for protocol be blank or would it already be filled out, because in that case, you're out of luck...

lidnariq
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Re: Super gameboy color?

Post by lidnariq » Fri Nov 06, 2015 7:15 pm

Woah nellie, before long you're going to be denying that computers could possibly work.

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Drew Sebastino
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Re: Super gameboy color?

Post by Drew Sebastino » Fri Nov 06, 2015 7:24 pm

What?

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tokumaru
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Re: Super gameboy color?

Post by tokumaru » Fri Nov 06, 2015 7:28 pm

Espozo wrote:Just one bit could mean either jumping back to the start of a loop or running off into nowhere...
Well, it's not like these 0s and 1s are raw data... Here's what Wikipedia says about CDs:
The pits and lands themselves do not directly represent the zeros and ones of binary data. Instead, non-return-to-zero, inverted encoding is used: a change from pit to land or land to pit indicates a one, while no change indicates a series of zeros. There must be at least two and no more than ten zeros between each one, which is defined by the length of the pit. This in turn is decoded by reversing the eight-to-fourteen modulation used in mastering the disc, and then reversing the cross-interleaved Reed–Solomon coding, finally revealing the raw data stored on the disc.
I have no idea what most of that means, but it's clear that the data goes through a lot of transformations so it can be read from the disc more reliably.

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Re: Super gameboy color?

Post by tepples » Fri Nov 06, 2015 10:07 pm

Espozo wrote:I've never quite understood as to how programs never catastrophically fail from reading off of something as seemingly unreliable as that.
It's called Reed-Solomon coding. If some bytes are illegible, the drive's controller does various polynomial voodoo in a finite field to guess the missing bytes. The same principle is used in 2D barcodes such as QR codes.

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mikejmoffitt
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Re: Super gameboy color?

Post by mikejmoffitt » Sat Nov 07, 2015 8:23 pm

tokumaru wrote:
Espozo wrote:Just one bit could mean either jumping back to the start of a loop or running off into nowhere...
Well, it's not like these 0s and 1s are raw data... Here's what Wikipedia says about CDs:
The pits and lands themselves do not directly represent the zeros and ones of binary data. Instead, non-return-to-zero, inverted encoding is used: a change from pit to land or land to pit indicates a one, while no change indicates a series of zeros. There must be at least two and no more than ten zeros between each one, which is defined by the length of the pit. This in turn is decoded by reversing the eight-to-fourteen modulation used in mastering the disc, and then reversing the cross-interleaved Reed–Solomon coding, finally revealing the raw data stored on the disc.
I have no idea what most of that means, but it's clear that the data goes through a lot of transformations so it can be read from the disc more reliably.
In short, from memory, each pit / opaque spot on a disc indicates an XOR with the previous bit state. That's what I remember from my A+ class form six years ago.

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Re: Super gameboy color?

Post by MottZilla » Thu Nov 12, 2015 1:56 pm

tokumaru wrote:I do know that the protection can be circumvented though, because there are people running games off of mini DVD-Rs.
Most GameCube consoles via software can affect the DVD drive controller to enable a standard DVD reading mode. I think later ones and all Wii consoles cannot do this via software anymore but there is a hardware (modchip) method of basically doing the same thing to enable reading standard DVDs.

Prior to this the GameCube actually had an interesting piece of software using Phantasy Star Online and the Broadband Adapter that allowed you to stream ISO images over your network to your GameCube. The only problem is the transfer rate or the method of transferring data did not work well with audio and video streams in many games.

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Re: Super gameboy color?

Post by LocalH » Fri Dec 18, 2015 10:00 pm

MottZilla wrote:I think later ones and all Wii consoles cannot do this via software anymore but there is a hardware (modchip) method of basically doing the same thing to enable reading standard DVDs.
I believe older Wiis allowed this, as there used to be a piece of homebrew called DVDX that installed a hidden channel enabling DVD Video commands to be sent to the drive. This was supplanted by a later release of Homebrew Channel, which incorporated the ability to do this (via the HW_AHBPROT flag) internally. Newer Wiis have drive firmware that will not read from any disc that is not an official Nintendo optical disc (GC or Wii) without a drivechip mod.

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Re: Super gameboy color?

Post by calima » Sat Feb 06, 2016 11:06 am

tokumaru wrote:
lidnariq wrote:Why not get a used gamecube and gameboy player?
I considered doing this, but optical drives have the annoying tendency to fail, and considering how old the GameCube is, I wouldn't expect a used one to last very long. If only you didn't need to use a disc in order to boot the Game Boy hardware...
Old topic, but this info wasn't mentioned in it so far, so:
There exists a GC drive replacement that takes SD cards. It was developed after the Wii had already come out, and mainly used for piracy of course, but if you're worried about the optical drive flaking out, try finding one of those. I forget what it was called though.

It was rather simple to install too IIRC, no soldering.

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Re: Super gameboy color?

Post by calima » Sat Feb 06, 2016 11:35 am

Oh, to the OP, there exist various third-party Gameboy players for many consoles. Here's one for SNES that can play GBA:
http://www.tototek.com/store/index.php? ... cts_id=168

Doesn't mention GBC support though.

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Myask
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Re: Super gameboy color?

Post by Myask » Tue Feb 09, 2016 5:51 pm

tokumaru wrote:
lidnariq wrote:Why not get a used gamecube and gameboy player?
I considered doing this, but optical drives have the annoying tendency to fail, and considering how old the GameCube is, I wouldn't expect a used one to last very long. If only you didn't need to use a disc in order to boot the Game Boy hardware...
The GBP disc is also "strangely rare" and therefore expensive.

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Re: Super gameboy color?

Post by mic_ » Thu Feb 11, 2016 8:36 am

The GBP disc is also "strangely rare" and therefore expensive.
That problem should at least be solvable with an SD Media Launcher.

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Guspaz
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Re: Super gameboy color?

Post by Guspaz » Mon May 09, 2016 10:15 am

For that matter, if you're using a modchip or Datel Media Launcher, there is no reason to use the GBP disc: GBI is better in pretty much every respect. Lower latency and native 240p support. All versions support using a GBA as a controller.

There are three builds:

ULL: Tries to very closely match the GBA refresh rate, and has essentially zero lag. Unfortunately many displays/upscalers either won't sync with this, or show monochrome, and occasional tearing will happen on all displays when the GBA and GC drift out of sync. But, 240p/480p output and no lag is reaaaally nice.

LL: A bit less of a close match to the GBA native refresh rate. More compatible, and solves the tearing by adding a rolling framebuffer for 1-2 frames of lag. Still has 240p support (not sure about 480p).

Regular: Standard refresh rates so works on any display, supports various types of scaling/borders/networking/colour adjustments/on-screen menu/etc. but has 2-3 frames of lag at 60Hz and 1.5-2 frames of lag at 120Hz (which requires HDMI mod, IIRC).

Personally, my PVM works great with ULL, and my particular GBP/GC exhibit the tearing only relatively rarely and for a relatively short amount of time, making it a tolerable tradeoff for the reduced lag.

EDIT: But yes, the GBP is generally cheaper to buy without the disc than with, since the disc is a lot more rare than the GBP. Since I planned to use GBI from the start, that didn't concern me, and I did burn a GBP disc anyhow for the heck of it.

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