The Facts
To play PSX games, referred to as "ROMs," on your device, you must "jailbreak" the device. Though not illegal, jailbreaking an iPod, iPhone or iPad violates Apple&'s terms of service agreement and will void the warranty. While you can reverse this process through iTunes--which will delete all jailbroken applications installed, returning the device to its original state--many users find the process time-consuming and frustrating. Jailbreaking involves locating a program online, and following the instructions given.
Requirements
Once you&'ve jailbroken your iPod Touch, you need to use Secure Shell or SSH to connect to and receive files from a website that offers ROMs of PlayStation games. Many ROMs come compressed in .RAR or .ZIP format, so you must have an unzipping program, such as WinRAR, which you can download for free online.
Disadvantages
Inherently slower and less visually appealing than their original counterparts, ROMs for the PSX will not run as well on your iPod Touch as they would on a PlayStation using the actual game disk(s). The "controller" will take up the entire lower half of the screen, and as with all applications that run on touch-based devices, there&'s no tactile feedback, which makes playing twitch-based games (such as shooters) difficult to control.
Identification
ROMs come in a variety of formats, with multiple parts. Some of the formats you might see include .CUE, .CCD, .IMG or .SUB. You must download all of the parts for each game, but regardless of the format the ROM was created in, it will still work on your device.
Intended Use
Sources for emulators and ROMs typically state that they provide such programs for review purposes only, and usually instruct users to delete each program within 24 hours of downloading. If the user has ownership of the original game and gaming platform, however, the user could legitimately keep a ROM for backup purposes.