A slot machine's theoretical payout percentage is set at the factory when the software is written. Changing the payout percentage after a slot machine has been placed on the gaming floor requires a physical swap of the software or "firmware", which is usually stored on an EPROM but may be loaded onto non-volatile random access memory (NVRAM) or even stored on CD-ROM or DVD, depending on the capabilities of the machine and the applicable regulations. In certain jurisdictions, such as New Jersey, the EPROM has a tamper-evident seal and can only be changed in the presence of Gaming Control Board officials. Other jurisdictions, including Nevada, randomly audit slot machines to ensure that they contain only approved software.