japanese PU-20 with psnee only plays NTSC-J backups

Post a topic about yourself to let others know your skills, hobbies, etc.
Post Reply
Franky1989
Interested PSXDEV User
Interested PSXDEV User
Posts: 5
Joined: April 8th, 2019, 9:27 am

japanese PU-20 with psnee only plays NTSC-J backups

Post by Franky1989 » April 8th, 2019, 9:57 am

Hello everyone,

I bought a Japanese PlayStation model SCPH-7000 whit a PU-20 board recently and i have modded it whit a Arduino pro-mini psnee v7.

The problem is that the PlayStation only plays NTSC-J backups and no PAL or NTSC-U.

I cant find any documentation to fix this problem.

rama3
/// PSXDEV | ELITE ///
/// PSXDEV | ELITE ///
Posts: 464
Joined: April 16th, 2017, 10:54 pm

Re: japanese PU-20 with psnee only plays NTSC-J backups

Post by rama3 » April 8th, 2019, 11:45 pm

This gets asked a lot, so I think I should include some info in the PsNee sketch.

The BIOS shell code in Japanese machines produced early 1995 and after has a region check in it.
It will not run out of region (PAL, NTSC-U) disks, even if they have been authorized by the modchip.
There are only workarounds, such as boot disks or expansion cards (anything that boots software, that can be started on such a machine).
The modchip itself can't do anything about it.

Franky1989
Interested PSXDEV User
Interested PSXDEV User
Posts: 5
Joined: April 8th, 2019, 9:27 am

Re: japanese PU-20 with psnee only plays NTSC-J backups

Post by Franky1989 » April 8th, 2019, 11:58 pm

Thanks fore the reply any suggestion where i can find a boot disk. And by expansion cards you mean like a gameshark ?

rama3
/// PSXDEV | ELITE ///
/// PSXDEV | ELITE ///
Posts: 464
Joined: April 16th, 2017, 10:54 pm

Re: japanese PU-20 with psnee only plays NTSC-J backups

Post by rama3 » April 9th, 2019, 3:45 am

Import Player Light (Google) is a good boot disk. It just has to have a Japan license sector. If you can't find an .iso with the correct license sector, another tool "setregion" can change it.

Yep, Gameshark, Xploder, any clone device, they'll all work for this.

User avatar
Squaresoft74
Extreme PSXDEV User
Extreme PSXDEV User
Posts: 159
Joined: January 7th, 2016, 2:55 am
PlayStation Model: SCPH-7502
Location: France
Contact:

Re: japanese PU-20 with psnee only plays NTSC-J backups

Post by Squaresoft74 » April 9th, 2019, 3:51 pm

rama3 wrote:
April 8th, 2019, 11:45 pm
The BIOS shell code in Japanese machines produced early 1995 and after has a region check in it.
Sorry for hijacking this topic but is this something similar to the PAL PSone bios extra check ?
If it is, no modchip acting like the Onechip does were ever made for Japanese consoles ?

rama3
/// PSXDEV | ELITE ///
/// PSXDEV | ELITE ///
Posts: 464
Joined: April 16th, 2017, 10:54 pm

Re: japanese PU-20 with psnee only plays NTSC-J backups

Post by rama3 » April 9th, 2019, 4:35 pm

The PAL PSOne check may be the same as they use for Japan, not sure.
The Japan BIOS is largely different from the other regions, so I guess the check is a little different as well.

In any case, the Onechip code is able to work around the protection by luck :p
It turns out that there is one region coding byte in the BIOS that gets transmitted to the CPU.
This byte is set to ASCII 'E' for PAL, and ASCII 'A' for NTSC-U.
If you check an ASCII table, there should be exactly one bit difference between the 2 symbols, and this bit will be 1 for Europe, 0 for USA.
Now the chip just has to time itself correctly, and drag down the data line that carries this bit at the right time.
The 'E' becomes an 'A' to the CPU, and since NTSC-U doesn't have the region lockout, it is successfully bypassed.

If the letters were reversed, this would be much harder to pull off. Dragging a bit low is easy, forcing one up, not so much :p

Anyway, this also means that any such check for an NTSC-J machine wouldn't work at all. The letter is too different.

User avatar
Squaresoft74
Extreme PSXDEV User
Extreme PSXDEV User
Posts: 159
Joined: January 7th, 2016, 2:55 am
PlayStation Model: SCPH-7502
Location: France
Contact:

Re: japanese PU-20 with psnee only plays NTSC-J backups

Post by Squaresoft74 » April 10th, 2019, 1:27 pm

Thank you for your explanation.

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest