PS1:Playing Game Backups

Universal prerequisite
You have a good copy of the disc correctly burned to a quality CD-R, an "Hong Kong Silver" industrially manufactured pirate, or an original foreign disc - and the disc and the console's drive are still in good condition.

If these are inconvenient or unacceptable, alternatives may exist (subject to commercial availability, a fat price, and model compatibility): refer to the main index at the Optical Drive Emulators section!

Plain swap trick

 * 1) The console is rigged to be able to change discs without it realizing the cover has been opened. This might be done:
 * 2) * By fitting another switch in parallel with the door sensor.
 * 3) * By adding cardboard or tape between the motherboard and shielding to always hold the actual button down. (not suitable for multi-disc titles)
 * 4) * By leaving the cover open and using a rubber or spring-loaded extension to the tab that pushes the button.
 * 5) * By creatively sawing off most of the cover.
 * 6) A compatible disc is inserted in the console, and accepted by it.
 * 7) At the right moment in the boot animation, the disc is swapped for the desired one.
 * 8) * On newer models, the double swap trick must be performed by re-swapping to the original disc and again to the wanted one with appropriate timing.

While not requiring any particular equipment, it has a number of disadvantages:
 * Tedious, and must be repeated for every disc change or reboot.
 * Requires fighting the motor. An externally fully braked but energized motor approaches a short circuit which may be stressful to the windings, mechanics, and driver electronics.
 * If improperly done, risks scratching the lens and/or disc.
 * The original disc's TOC may be used, introducing compatibility problems depending on the relative contents of the two discs.

Facilitated swap trick
Many cheat devices, and even some commercial discs dedicated to the purpose (like "Swap Magic"), have a more or less deliberate feature to stop the motor, avoiding the risks of the above and the eventual need to perform a double swap.

Modchips
Devices which substitute to the optical drive for providing the 4-letter region string.

Invented in Hong Kong in early 1996 and sold for a relatively high price, one of them was eventually cloned by the Old Crow opening the floodgates.

By the 2010s there were 3 main chips still available - the Mayumi, the MM3 (MultiMode3), and the OneChip (for Slims, which also bypasses the BIOS-based protection on SCPH-102). Last but very far from least, the Arduino-based PSNee launched in mid 2017 (general purpose plus 102) and its 2021 derivative PSNee V8 (which also bypasses the Japanese BIOS protection).

Non-stealth
A non-stealth chip continuously generates the region signal, making it less accurate and detectable (unless manually switched); on the other hand, a non-stealth chip tends to be easier to install (having less wires to connect: power, ground, data, gating to chip or fixed pulldown) and more compatible across models (3-wire setups happen to work on PS2, connecting to "SX" line).

Stealth
A stealth chip uses some mechanism (a fixed delay, or better actual knowledge of the current position on disc thanks to subchannel data) to stop when unneeded.

All five chips mentioned above are stealth when installed according to their complete instructions.

Nocash Unlock
Named after Nocash (Martin Korth: the NO$* emulator developer) who discovered it in 2013.

The optical drive controller of (non-Japanese) PS1s will disable disc checks until its next reset if it receives a specific series of commands.

This can be achieved with any arbitrary code execution method, though most practically this will mean a parallel-port option ROM or a BIOS exploit (PS1:FreePSXBoot), distantly followed by a game exploit like PS1:Tonyhax.