Hardware Homebrew PS1/2 Why doesn't the PSOne have much support in the modding scene?

[Gallaer]

I was curious on why the PSOne (PS1 Slim) lacked in any sort of hard mods outside of a modchip. There are no optical drive emulators and no HDMI solutions for it. There is also stuff like the PSIO for early PS1 systems. I understand why the PSIO specifically isn't available for the one, but nothing else similar to it is available?
Would it be possible to load games off an SD Card similar to the GameCube and use a burned disc to load into a sort of Homebrew menu? Is this just too much for the system to handle?

 

[godreborn]

There's the Tony hawk hack iirc, which is like from 2019, so it's still active.

 

[Gallaer]

There's the Tony hawk hack iirc, which is like from 2019, so it's still active.

But that's about it besides basic modchips.

 

[Hayato213]

There are no optical drive emulators and no HDMI solutions for it.

You have xstation for the optical drives emulation and PS1 Digital for HDMI.

 

[Gallaer]

You have xstation for the optical drives emulation and PS1 Digital for HDMI.

I was talking about the PSOne

 

[master801]

Different hardware was used for the PSOne.

Dedicated chips used in the original PS1 were eventually condensed into 1 chip handling multiple processes.

https://playstationdev.wiki/ps1devwiki/CD_controller
https://playstationdev.wiki/ps1devwiki/CD_DSP

https://playstationdev.wiki/ps1devwiki/Motherboards

 

[Hayato213]

I was talking about the PSOne

Those are for PS1

 

[Gallaer]

Those are for PS1

Not the original PS1, the PSOne (PS1 Slim)

Post automatically merged: Apr 4, 2023

Different hardware was used for the PSOne.

Dedicated chips used in the original PS1 were eventually condensed into 1 chip handling multiple processes.

https://playstationdev.wiki/ps1devwiki/CD_controller
https://playstationdev.wiki/ps1devwiki/CD_DSP

https://playstationdev.wiki/ps1devwiki/Motherboards

Do you think it'd be possible to make an HDMI mod or Equivalent to the Xstation for the One?

 

[RAHelllord]

The creator behind the xstation is still working on a new ODE that would be compatible with the PSOne as well, but as far as I know it's still in the research phase.

 

[master801]

Not the original PS1, the PSOne (PS1 Slim)

Post automatically merged: Apr 4, 2023

Do you think it'd be possible to make an HDMI mod or Equivalent to the Xstation for the One?

HDMI mod? Sure. Not sure if it would be worth the effort since the older PS1s are more commonly found.

ODE? Unlikely, unless someone actually makes a literal ODE (optical disc emulator) emulating the actual disc instead of re-implementing or hijacking the pre-existing drive controller - which I think is what that Twitter video is showing.

From memory, the PSIO team also has some prototype ODE like that, emulating the literal disc. The biggest trouble implementing something like that in my opinion, would be the "wobble" the PS1 expects.

https://problemkaputt.de/psx-spx.htm#cdromprotectionscexstrings

Another issue -albeit a very small issue- would be bypassing the region locking in Japanese PS1s. These have the BIOS explicitly checking disc region unlike USA and Europe BIOS versions.
https://problemkaputt.de/psx-spx.htm#cdromisovolumedescriptors
https://www.psxdev.net/forum/viewtopic.php?t=1485

 

[KleinesSinchen]

From memory, the PSIO team also has some prototype ODE like that, emulating the literal disc. The biggest trouble implementing something like that in my opinion, would be the "wobble" the PS1 expects.

The SCEx protection probably isn't the most complicated thing. After all an ODE could just include modchip functionality sending the "wobble code" each time moving the virtual reading head to TOC.

I'd expect this to be more of a problem:

Dedicated chips used in the original PS1 were eventually condensed into 1 chip handling multiple processes.

The dream would be a "plug in replacement". I don't know at which point of data processing the current PS1 ODEs intercept.

Half-knowledge at best ahead (no warranty for correctness):

If you want to just unplug the drive and plug in an ODE (maybe with passthrough mode for keeping the drive alongside), the ODE would have to send all RAW data the optical pickup generates when reading a disc (then the tracking data would be no problem to fake satisfying the SCEx check). This means the 14-bit representation (EFM modulation) and the C1/C2 stage error correction. An image file on a computer does not contain the needed data.
To my knowledge it would require the ODE to have an EFM implementation and a Reed-Solomon encoder for providing the needed data on the fly just by a given image.

 

[master801]

The SCEx protection probably isn't the most complicated thing. After all an ODE could just include modchip functionality sending the "wobble code" each time moving the virtual reading head to TOC.

I'd expect this to be more of a problem:

The dream would be a "plug in replacement". I don't know at which point of data processing the current PS1 ODEs intercept.

Half-knowledge at best ahead (no warranty for correctness):

If you want to just unplug the drive and plug in an ODE (maybe with passthrough mode for keeping the drive alongside), the ODE would have to send all RAW data the optical pickup generates when reading a disc (then the tracking data would be no problem to fake satisfying the SCEx check). This means the 14-bit representation (EFM modulation) and the C1/C2 stage error correction. An image file on a computer does not contain the needed data.
To my knowledge it would require the ODE to have an EFM implementation and a Reed-Solomon encoder for providing the needed data on the fly just by a given image.

Maybe. Who knows.

https://www.psxdev.net/forum/viewtopic.php?f=70&t=1266&sid=7c65090d7c62adddb598088981b9c03b

 

[KleinesSinchen]

Maybe. Who knows.

https://www.psxdev.net/forum/viewtopic.php?f=70&t=1266&sid=7c65090d7c62adddb598088981b9c03b

I know this thread almost word by word. *Sigh* And it went nowhere. *Sigh*
Producing actual discs containing the SCEx protection is hard (and probably requires physically wobbling the writing laser). Sadly missing the expertise here. Commonly mentioned as argument against burning "wobble" is the already wobbled pregroove of a "blank" CD-R. (ATIP wobble has very low amplitude though)
Commonly mentioned as argument for it is that video by MVG where he claims a software mod, simply CFW, on an old Plextor would have produced self-booting discs (I doubt it, but can't fully rule it out -- sadly nobody ever showed an unmodded PS1 starting a CD-R like an original to my knowledge).

If you are already hardware modding the console with an ODE, modchip functionality probably isn't the hardest part -- after all modchips are common since 1996 or so.

 

[RAHelllord]

The SCEx protection probably isn't the most complicated thing. After all an ODE could just include modchip functionality sending the "wobble code" each time moving the virtual reading head to TOC.

I'd expect this to be more of a problem:

The dream would be a "plug in replacement". I don't know at which point of data processing the current PS1 ODEs intercept.

Half-knowledge at best ahead (no warranty for correctness):

If you want to just unplug the drive and plug in an ODE (maybe with passthrough mode for keeping the drive alongside), the ODE would have to send all RAW data the optical pickup generates when reading a disc (then the tracking data would be no problem to fake satisfying the SCEx check). This means the 14-bit representation (EFM modulation) and the C1/C2 stage error correction. An image file on a computer does not contain the needed data.
To my knowledge it would require the ODE to have an EFM implementation and a Reed-Solomon encoder for providing the needed data on the fly just by a given image.

The tweet I linked earlier does actually go into detail with that, and emulates a reed-solomon encoder plus all the other stuff needed to successfully pretend to be a real drive.

 

[KleinesSinchen]

The tweet I linked earlier does actually go into detail with that, and emulates a reed-solomon encoder plus all the other stuff needed to successfully pretend to be a real drive.

Didn't open Twitter link. I have this platform blocked on my computers and unblocking it is tedious.

Sounds good! The task is pretty complex: EFM, Reed-Solomon, scrambler, all the optical drive specific hardware commands to implement.

Good luck for anybody attempting this. As the PS1 drives are more or less compatible to each other, a perfect emulator should work on any model -- including the slim PSOne.