ROM, Read-Only Memory, are memory chips that do not require a constant source (non-volatile) of power, whereas RAM, Random Access Memory, require a constant source of power (volatile).

ROM chips store the computer's hardware information for the CPU (Central Processing Unit) to read during power up. Typically, these chips are programmed at the factory, very slow to load, and cannot be altered. Recent advances introduced the EEPROM (electrically erasable programmable read-only memory) that allows changes in the operations / memory storage. Early PC's used a BIOS (Basic Input/Output System) ROM, while today's computer utilizes "flash memory" (a type of ROM and RAM chip). The CPU accesses the information in the BIOS at startup to determine the firmware configuration of the computer.

RAM chips store information "on the fly" for programs, applications, and other non-permanent functions of the CPU and other devices. The information is written at greater speed for quicker access by the CPU to perform the functions requested by the computer operator. Once an application is closed, it is erased until the application is started again.

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