News: 11 March 2016 - Forum Rules
Current Moderators - DarkSol, KingMike, MathOnNapkins, Azkadellia, Danke

Author Topic: PSX romhacks and ECC Data:  (Read 1966 times)

TimeCop

  • Jr. Member
  • **
  • Posts: 45
    • View Profile
PSX romhacks and ECC Data:
« on: April 07, 2017, 09:08:05 pm »
Some PSX romhacks break the ECC Data. This results in those romhacks not working on both real hardware and accurate emulators. Typically they're only testing the romhacks in something like epsxe, which doesn't care abou ECC Data.

All hope is not lost however. To fix this, users can use tools like ECCregen to repair the game after patching to make the games work. However, this is an extra step that adds complication to the patching process, and is completely uneeded if romhackers had just patched their games properly in the first place.

So, get the word out that PSX romhacks should patch the ECC data as well, and to test the romhacks either on real hardware (ideally) or high accurate emulators.

Also, romhacks that make use of ASM hacks, do not work on real hardware under any circumstances as far as I know.

« Last Edit: April 07, 2017, 09:18:20 pm by TimeCop »

FAST6191

  • Hero Member
  • *****
  • Posts: 2626
    • View Profile
Re: PSX romhacks and ECC Data:
« Reply #1 on: April 08, 2017, 05:26:48 am »
Many of the kids today are probably familiar with having to decrypt ROMs to apply patches, this could be written off under that.

The assembly hack thing has me curious though, especially as I imagine the gamesharks on the hardware went there at various levels. Doubtless some mods would probably trip anti piracy but as a general concept I am not so sure.
Are there any binary checksums/hashes involved? Given the... less concerned approach to security of the time it would probably only do on load patching rather than constant checks too, not to mention a quick scan of http://problemkaputt.de/psx-spx.htm#expansionportpio mentions other things so it would more likely be a chain loader.

Edit. Probably should have read the protection chapters as well http://problemkaputt.de/psx-spx.htm#cdromprotectionscexstrings and onwards for a few, including some stuff about XOR decryption in some games.

Gemini

  • Hero Member
  • *****
  • Posts: 2017
  • 時を越えよう、そして彼女の元に戻ろう
    • View Profile
    • Apple of Eden
Re: PSX romhacks and ECC Data:
« Reply #2 on: April 08, 2017, 05:50:05 am »
Also, romhacks that make use of ASM hacks, do not work on real hardware under any circumstances as far as I know.
That's more like a problem of the past when people used spasm to assemble injection code, also something a lot harder to fix than simple control data on disk. Fortunately illegal code can be fixed with armips, which does have checks for hardware compatibility and can detect common issues like broken delay slots. ECC/EDC can be fixed with a scansion, takes really a minute to do so and it's all automatic.
I am the lord, you all know my name, now. I got it all: cash, money, and fame.

paul_met

  • Full Member
  • ***
  • Posts: 197
    • View Profile
    • Meduza Team
Re: PSX romhacks and ECC Data:
« Reply #3 on: April 08, 2017, 11:02:18 am »
Some PSX romhacks break the ECC Data. This results in those romhacks not working on both real hardware and accurate emulators. Typically they're only testing the romhacks in something like epsxe, which doesn't care abou ECC Data.
Just use CDMage to insert modified files back to image. This tool automatically recalculates ECC/EDC data. Voila.

TimeCop

  • Jr. Member
  • **
  • Posts: 45
    • View Profile
Re: PSX romhacks and ECC Data:
« Reply #4 on: April 13, 2017, 04:26:22 pm »
The problem is emulators like epsxe allowing this to happen, and people only test in epsxe.

NERV Agent

  • Restricted Access
  • Sr. Member
  • *
  • Posts: 497
  • Eva Unit 01
    • View Profile
    • Watch my anime shitposts on YouTube! Smell them, too!
Re: PSX romhacks and ECC Data:
« Reply #5 on: April 14, 2017, 04:54:37 pm »
Er, once upon a time I was able to run a ROM hack of Tomb Raider II PSX on real hardware, without using ECCregen.

I struggled while trying to get it to work at all, but finally got it to work when I followed these instructions.

Unless this is a special case, and some PSX hacks require ECCregen and others do not? Has a list of this been compiled?

SCO

  • Full Member
  • ***
  • Posts: 131
    • View Profile
Re: PSX romhacks and ECC Data:
« Reply #6 on: April 15, 2017, 06:37:12 am »
Uh. I didn't know about ECCRegen so i then asked here for a tool like that, and someone provided:
http://www.romhacking.net/utilities/1264/

Used it to fix the brigantine grand edition translation (out of site) and the iS - internal Sector translation (in-site) so they worked on retroarch mednafen.