Part of a computer’s memory is microchips built in at the factory and known as ROM, or read-only memory. ROM carries the basic working instructions.
RAM (random-access memory) consists of microchips that receive new data and instructions when needed.
Data can also be stored as magnetic patterns on a removable floppy disk, or on the laser-guided bumps on a CD (compact disc) or DVD (digital versatile disk).
At the heart of every computer is a powerful microchip called the central processing unit, or CPU.
The CPU performs logical and mathematical operations on data, within the guidelines set by the computer’s ROM. It carries out programs by sending data to the right place in the RAM.
Computers store information in bits (binary digits), either as 0 or 1. The bits 0 and 1 are equivalent to the OFF and ON of electric current flow. Eight bits make a byte. A kilobyte is 1000 bytes; a megabyte (MB) is 1,000,000 bytes; a gigabyte (GB) is 1,000,000,000 bytes; a terabyte (TB) is 1,000,000,000,000 bytes.
The US Library of Congress’s 70 million books could be stored in 25 TB of computer capacity.
A CD can hold about 600 MB of data — approximately 375,000 pages of ordinary text.