RAM

Random Access Memory, or RAM (pronounced as ramm), is the physical hardware inside a computer that temporarily stores data, serving as the computer's "working" memory.

Additional RAM allows a computer to work with more information at the same time, which usually has a dramatic effect on total system performance.

ROM

ROM is "built-in" computer memory containing data that normally can only be read, not written to. ROM contains the programming that allows your computer to be "booted up" or regenerated each time you turn it on. Unlike a computer's random access memory (RAM), the data in ROM is not lost when the computer power is turned off. The ROM is sustained by a small long-life battery in your computer.

If you ever do the hardware setup procedure with your computer, you effectively will be writing to ROM.

PROM:

Proms are commonly known as JS prom, or, junior–senior prom. Conversely, if a high school has separate dances for juniors and seniors, the term "prom" is reserved for the juniors, and the dance for the seniors is called a "graduation ball" (often abbreviated as "grad ball" or simply "ball".)

Magnetic Disk

A magnetic disk is a storage device that uses a magnetization process to write, rewrite and access data. It is covered with a magnetic coating and stores data in the form of tracks, spots and sectors. Hard disks, zip disks and floppy disks are common examples of magnetic disks.