The PS1-ROM.BIN file is a binary file that contains the PS1 BIOS, which is responsible for initializing the PS1 hardware and providing a layer of abstraction between the PS1 games and the PS3 hardware. This file is essential for playing PS1 games on the PS3, as it allows the console to accurately emulate the PS1 environment.
The file was just a sequence of hex code named Ps1-rom.bin , tucked away in a dusty corner of a forum thread from 2008. To most, it was just a piece of the PlayStation 3's "backward compatibility" firmware. To Elias, it was a ghost in the machine.