bytes per second that the RAM can be written and read from. This is data that must be transferred to and from the CPU and GPU quickly as needed without requiring these chips to need high memory caches themselves. Internal storage Newer consoles have included internal storage devices, such as flash memory, hard disk drives (HDD) and solid-state drives (SSD), to save data persistently. Early application of internal storage was for saving game states, and more recently can be used to store the console's operating system, game patches and updates, games downloaded through the Internet, additional content for those games, and additional media such as purchased movies and music. Most consoles provide the means to manage the data on this storage while respecting the copyrights on the system. Newer consoles, such as the PlayStation 5 and Xbox Series X, use high-speed SSD's not only for storage but to augment the console's RAM, as the combination of their I/O speeds and the use of decompression routines build into the system software give overall read speeds that approach that of the onboard RAM. Power supply Besides converting AC power from a wall socket to the DC power needed by the console electronics, the power supply also helps to regulate that power in cases of power surges. Some consoles power supplies are built into the unit, so that the consumer plugs the unit directly to a wall socket, but more often, the console ships with an AC adapter, colloquially known as a "power brick", that converts the power outside of the unit. On handheld units the power supply will either be from a battery compartment, or optionally from a direct power connection from an AC adapter, or from a rechargeable battery pack built into the unit. Cooling systems More advanced computing systems generate heat, and require active cooling systems to keep the hardware at safe operating temperatures. Many newer consoles are designed with cooling fans, engineered cooling fins, internal layouts, and strategically-placed vents on the casing to assure good convective heat transfer for keeping the internal components cool. Media reader Since the introduction of game cartridges, nearly all consoles have a cartridge port/reader or an optical drive for game media. In the latter console generations, some console revisions have offered options without a media reader as a means to reduce the console's cost and letting the consumer rely on digital distribution for game