Want to boot a PSX without using a CD?
Early versions of the PSX (not the PS1) has a cartridge port at the rear-right of the console. You can buy cheat cartridges that plug in the back of the machine and boot when the machine starts, they usually cost just less than £5. You can actually put your own code on one of these cartridges and thus make your own boot game or system instantly. The PSX checks the cartridge port to make sure that its a valid system before it will boot.