PS-X homebrew cdrom master with Wobble Groove data

Has anyone ask CD duplicators about CDROM mastering which can press CDs (not burn CDRs - replicators) with the PS-X wobble groove data? (the nanometers thin range near the center of the disc).

I'm sure they would do it, at a cost and a decent press run (1k+), I guess.
I'm asking around my area.

 

For what purpose, are you a developer?

Not sure if they still exist in any capacity, but look into Thin Ice Media. Back in the day, these guys were responsible for pressing (I think) the Gameshark and Action Replay discs for PSone and 2.

 

Thanks man!
yeah, for homebrew.. just wondering if it's possible at this stage.
I think Thin Ice Media is now datel?
http://datel.co.uk/pages/Development.aspx

I emailed them asking if they would do 'indie' runs but they never got back to me

 

Thin Ice Media was always Datel - they called it that because they were well aware they were operating in something of a legal grey area.

According to someone I talked to who used to work for Sony DADC they had some specific machines that they used for making PlayStation glass masters - the machines could also be used for making other kinds of CDs, but were modified with a specific operating mode for recording the PSX wobble data - there was a similar arrangement for the PS2. Once they had the glass master, the rest of the disc manufacturing process was identical to any other disc except for the substrate material, which was visually black but transparent to IR light.

Also note that the frequency of the wobble is (presumably deliberately) very close to the wobble used on a CD-R pregroove to control the disc speed during the writing process. which is why you can't make a CD-R with this data pre-recorded on it.

 

I haven't thought about PlayStation copy protection in years. Hypothetically, is it possible to alter a CD burner (firmware, maybe) in some way to overwrite this area on the disc?

 

I might be getting my history mixed up, but didn't Datel "grow" their own bootable discs by replicating the wobble from an official disc and physically fusing it with the data they wanted to boot?

 

You might be thinking of Action Replay for Gamecube.

 

yeah i think they used an EA sports game data (NHL???) on the GameCube to get the boot code, apparently it was just enough to ensure boot compatability which kept them on the right side of the law, so long ago now cant remember exactly

the PSX discs that you may be thinking of were the boot discs that were released at the end of the PSX life, rumours said they cut the wobble from an original disc and added it into the boot disc but i cant see it myself, however happy to be proven wrong

 

That trick of using the inner ring of a original disc was done on PS2 discs because there's more data than just the license letters encoded on the "wooble" there.
You need that "wooble" data (it matches the DISC ID, which happens to be the name given to the boot file for the disc) to be correct and it is why PS2 datel DISCs had IDs taken from proper retail games (Crazy Taxi, TimeSplitters and other early CD-ROM titles). Without that data the "PlayStation 2" logo won't xor properly and the game elf file won't start even if the disc managed to unlock the drive for low level data access.

 

All CD's wobble, PSX just has a data signal modulated on the wobble.

https://en.wikipedia.org/wiki/Wobble_frequency

All you need to do is change from a hard coded sine wave, to waveform that includes the region (or regions) you want to boot (I have a boot disc that will boot on any region)

The reason why you can't burn it onto a CD-R is that the wobble is pre-determined and is required for writing. It's not like a wax disk that you're scratching a track into wherever you want.

 

Actually, the "blank" which is used to make the "positive" which will then press the final plastic discs is actually a sort of "wax disc" made of a thin layer of gold and then glass as substrate. The mastering laser burn holes on the gold and that is filled with the other metal (nickel? tin?) which is used to then form the positive mask which will be used to make the final consumer discs. What I believe trimesh meant is that the actual mastering equipment had it's firmware modified to in addition to encode the standard information required for the standard disc mastering, it would do the PlayStation wobble imprint on the glass master.

 

No, only the recordable discs have wobble - I can absolutely assure you that a regular audio CD or CR-ROM has a linear spiral, which is precisely why Sony were able to put a modulated wobble onto the PSX discs without affecting anything. The reason you can't do it on a CD-R is that they *do* have a wobble and it has to be constant and continuous for the entire pregroove because it's the reference signal for the spindle servo when writing.

 

Is it theoretically possible that, maybe one day, there will be a solution for producing self-booting PlayStation homebrew from a backup disc?

 

No idea if that's actually feasible, but you are probably better off with an AR cartridge and some code to unlock the console via CD commands. I guess the only down side to that is that PSone would be locked out due to having no expansion port.

 

As smf pointed out, writable discs already have a wooble in them while blank (PS1 use a different kind of modulation for the signal than what CDR do and one would interfere with the other, aka you can't have both at the same time) and the wooble isn't writable either.

 

http://www.psxdev.net/forum/viewtopic.php?f=24&t=967

I haven't tried it myself, but kind of defeats the purpose... I imagine an AR cart is harder to get then a mod chip and installer :/


Anyone know if the Sony PS1 CDR's had the Sony wobble on them also?

 

An AR cart isn't really that hard to find, plus you can pretty much reuse it on any console laying around, which makes it a lot more versatile and easier to deal with than a mod chip.

 

No, they were perfectly standard CD-Rs, which is why they only booted on debug stations.

I guess you might be able to make a CD-R with this data on it, but it would require a special recorder - without getting into too much detail, the basic problem with CD-Rs is that the recorder has to know how fast the disc is spinning. On a regular CD, the speed is controlled by monitoring the symbol rate out of the EFM decoder, and adjusting the spindle speed until this matches the required data rate.

This obviously won't work on a CD-R, because until it's recorded there is no data to monitor - and the solution that was chosen was to put a wobble on the pregroove in the disc that the recorder could pick up - this is also modulated to carry address information, since that normally comes from the subcode in a CD-R, and again there is no subcode until the disc has been written (the "ATIP" is a special case of this - it's an encoded value that's written in place of the normal ADIP information in the disc lead-in so that the recorder can identifiy the type of disc).

So the basic problem is that this stuff is required on a pretty fundamental level for a CD-R to work - and the license data on the PSX is written in a way that would interfere with it (this is possibly deliberate...) - if you get one of the old PlayStations with the discrete component copy protection circuit, it's pretty easy to see this - if you play a regular audio CD then the output of this filter is basically just a little bit of low-level noise - but if you play a CD-R (even an audio one) there is a rather large constant signal coming out of this filter, which would make the license data basically impossible to recover.

One interesting side effect of this is that if you have one of these old units with the discrete protection circuit and the wire that's supposed to ground out the input of the comparator comes off then you end up with a machine that will only boot pressed copies (I.E. "HK silvers"), and will reject both CD-Rs and original discs (because in both cases the wobble on the disc interferes with the modchip signal).

 

Does the PSX check the wobble at a certain place on the cdrom? ie the laser travels to the center of the CD?
Does the PSX reader read/check the whole cd from start to end?

Edit: TOC info: http://www.herongyang.com/CD-DVD/CD-TOC-Where-Is-Located.html

 

The wobble is recorded in the ToC area of the disc and possibly at the end of the leadin, too. On all the discs I've looked at, it stops during the pregap for the first track, and hence is not present in any part of the user data area of the disc.

This makes a lot of sense, since according to the ToC a PlayStation CD is simply an CD-ROM XA disc, and hence the CD controller has to know if this is a licensed disc before it finishes reading the ToC so it can distinguish between an XA CD-ROM and a PlayStation game.

The other demonstration that the wobble is not present in the user area is given by Sony's modchip detection code - that seeks the drive into the user area, goes into x1 play mode and then starts looking for license strings, relying on the fact that an authentic disc does not have a license wobble in this area, but the early modchips just kept on sending.