Read Only Memory (ROM) was invented circa 1956. It is a storage device that is made and sold pre-programmed. ROM is an important element in electronics such as computers, video games, microwaves, and cell phones. In the computer, the motherboard houses ROM and connects it to other components of the computer. ROM is known to be nonvolatile as opposed to the Random Access Memory which is volatile. This means that the ROM maintains all of its information even when the computer is shut off. ROM is powered by its own battery. Another difference between ROM and RAM is that the information stored on ROM can only be read where as the information stored on RAM can be read and written. It is very difficult to adjust the contents of the ROM, but this can help prevent viruses. The basic functions of a computer, programs for calculators, and programs for devices such as the Peripherals are generally stored on ROM. For instance the ROM is used for booting up a computer. Not only is ROM extremely important for computers and other electronics, ROM is inexpensive and runs on very little power.
Around the same time ROM was invented, a storage device called PROM (Programmable Read Only Memory) was introduced as well. PROM is a memory chip that can be programmed by the user. But, one can only program PROM once and after that the information cannot be changed or deleted. Another version of ROM is the EPROM (Erasable Programmable Read Only Memory). The EPROM is a memory chip similar to the PROM except that It can also be erased and then reprogrammed.