The are two major differences between RAM (random access memory) and ROM (read-only memory). The first is that RAM requires a power source to retain its information, whereas ROM can retain its information when its power source is removed. Secondly they differ in the tasks they are used for, with ROM used to store programs and files and stockpile the data needed to run them. Any data created, or needed, by them to perform their allotted task is held in RAM.
The most common type of programmable ROM chip in a computer is the BIOS (basic input/output system), which is responsible for testing and powering up any hardware. It will then locate the operating system, load it and give it control of the computer's systems. RAM is generally in the form of a chip, while ROM is composed of magnetic tapes. RAM is also significantly larger and more expensive than the equivalent amount of ROM. There are two types of RAM: statistic RAM (SRAM) and dynamic RAM (DRAM). The three types of ROM are: PROM (programmable read-only memory), EPROM (erasable programmable read-only memory) and EEPROM (electrically erasable programmable read only memory). The oldest form of ROM dates back to 1932.