Selfbootable #ps1 CD-R! No modchip! #homebrew #playstation #omg

Channel:

NickMoses05

Subscribers:

3,840

Published on June 24, 2023 4:58:22 AM ● Video Link: https://www.youtube.com/watch?v=lhrcTIAYSIU

Game:

Kula World (1998)

Category:

Let's Play

Duration: 0:19

458 views

18

Courtesy of David4599

OMG IT WORKS!! 🥳 Selfbootable #PS1 CD-R! No modchip!
That's a huge progress since last time but there are big reliability issues and I'm not sure that this can be fixed using my method. Increase the sound to hear the PS1 struggling to read the disc. More details below.

That's a long time since I didn't post so here is a big update of the project: about the burner's firmware, almost 40% of the 1900 functions are more or less understood! I don't think to go higher than 50%. Low-level sectors reading and writing, OPC, etc are too hard to reverse.

However, this is enough to do cool mods (and also damaging the laser diode... yep, that happened :( I think this is fixable though but I need to spend time on that, fortunately I have a spare burner to continue experimenting).

Now, for the wobble recreation, I can finally burn the entire SCEx pattern in the lead-in area. As said in a previous tweet, this method destroys some lead-in data and the PS1 struggle to read the game's TOC but rarely, it works! :D

BUT there are still several issues making the wobble reading not reliable. The most annoying one is that the pattern is fading in the middle of the lead-in, which is almost each time where the PS1 seeks to read the wobble. See the pink trace and the incomplete yellow SCEE signal.

I think this issue is tied to how the tracking mechanism of the CD drive works and the light differences received by the photodiodes. It's even worse when the disc is really warped. Still searching a solution.

Another issue is the increased disc speed. By modding another feature of the burner, it is possible to increase significantly the pits and lands length which will natively increase the PS1's motor speed (the goal is to stop detecting the original wobble as said in an old tweet).


The downside is that this will lower the writing and reading quality. We can clearly see and hear that issue in the video. Moreover, the actual motor speed in 2x speed is around 3x so the reading is even less reliable. I have a solution in mind but I'm not sure of the result.

Also, I may have found another method to "burn" the wobble by altering the tracking signal while burning (no overwriting). This should be possible to do in hardware by injecting a signal to the tracking coils but I am less good in hardware and I don't wan't to fry something.

Instead, I found a DSP command to adjust the tracking balance and by adding some code to the firmware, I can change the value of it really fast (3kHz) while burning. That way, the PS1 is able to see the 3kHz signal almost like is doing a real PS1 game.

Obviously, 3kHz is not enough for the minimum required (around 18-20kHz) for good wobble detection and this is still in research. I am planning to write some sort of blog posts but I will need a few weeks/months because there are so many things to document.

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