Stealth Unlocker (July 21st 2022)
For Playstation
By: MottZilla

Stealth Unlocker is an Expansion ROM that can be installed on a Parallel I/O Port Cartridge such as
the GameShark to boot Unlicensed or Import discs and supports all console regions. No visual changes
to the console startup process are present and everything looks normal.

Features:

+ American, European, and Net Yaroze Consoles
* CD-ROM drive is unlocked and will boot Unlicensed and Import discs.

+ Japanese and Asian non-Japanese (SCPH-XXX3)
* License Data Region lockout on Japanese consoles is removed and will boot PAL & NTSC/U discs.
* CD Player swap trick is restored to enable booting Unlicensed and Import discs.
  See below for swap trick details.
* Swap Trick performance improvements including correct CD audio track playback and laser calibration.
* Note: These consoles don't have the secret unlock in their CD-ROM controller.

Installation:

The easiest method to install Stealth Unlocker is by using the ISO image with NXFlash program to
write the ROM onto a Cheat Device with EEPROM or Flash memory. You will need a way of booting the CD-R
once in order to do this. Access to a modchipped system, swap trick, FreePSXBoot are all possibilities.

Unirom running from FreePSXBoot or Boot CD can be used with a serial cable and the plain ROM file.

Lastly you could program the ROM file to an EEPROM or FlashROM and install it into your Cartridge via
soldering or socket. Some cheap clones of Cheat Devices may use EPROM and require this method to use
them with Stealth Unlocker as you will not be able to reprogram an EPROM with the console itself. Also
if desired you can use a smaller ROM chip than 256KB. Currently 8KB of ROM would be large enough.

Swap Trick:
The swap trick is a method to bypass the security mechanism of the CD-ROM drive. By using a variety of
options to hold the lid sensor switch down you can change from a Licensed disc to an Import or
Unlicensed disc without the security check being performed on it. Only consoles with CD-ROM Controllers
of 'vC1 (a)' or older can do this trick using the CD Player menu normally but Stealth Unlocker allows
Japanese and Asian consoles of newer versions to use it too.

The swap trick has a couple problems which Stealth Unlocker fixes. First and most well known is the
swap trick will result in terrible audio problems with games that use CDDA tracks for music because the
Table of Contents containing the number of and position of audio tracks was read from the Licensed disc
and not the one you swapped in after. Stealth Unlocker fixes this issue, although the oldest models
such as SCPH-1000 and SCPH-3000 may require additional fixes due to a bug in the console itself. This
might get addressed in a future version. For consoles SCPH-5000 and newer it should work perfectly.

The second issue caused by the swap trick is on newer CD-ROM controllers the laser calibrates when the
lid is closed and the disc spins up. When you swap to your Import or Unlicensed disc the reading
performance of the laser may be noticeably worse. Stealth Unlocker fixes this by causing the calibration
sequence to occur after the swap trick.

How to do the Swap Trick:
* Power on the console with the lid open. Wait for the Main Menu and select the CD Player option.
* Place an original Licensed disc in the drive and hold down the lid sensor switch.
* Wait for the disc to spin up and then stop spinning.
* Remove the Licensed disc and place your Import or Unlicensed disc in the console.
* Exit the CD Player menu and your disc will boot.

Holding down the Lid Sensor:
There are many options for holding down the lid sensor switch. The important points are to use something
secure that won't come loose or hit the spinning disc and to use something that will allow you to close
the lid after putting in your unlicensed disc. The most popular choice is probably a spring. You can get
a spring that will keep the switch pushed down with the lid open by placing the spring around the pole
that normally pushes the switch down when the lid is closed. You might be able to use a spring from a
pen that is out of ink or from some other junk. 

Special Thanks to:
Alex-Free - Beta Testing & More
NoCash aka Martin Korth - No$PSX Emulator and Documentation
