Computer hardware such as modems or network interface cards, and computer software such as Telnet, Netscape or ProComm help computers communicate. Hardcopy output can be held in your hand, softcopy output is typically video or audio in nature. Although nearly all computers are able to perform the same basic operations, each is designed with specific capabilities and purposes in mind. Generally quite expensive, with fast processors and a lot of main memory, supercomputers are typically used in weather forecasting, petroleum exploration, scientific research, and other such number crunching activities. Mainframe computers can support the processing needs of hundreds, even thousands, of concurrent users.
Minicomputers are smaller, less powerful, and less expensive than mainframes.
A new minicomputer may be as small as an end table, but as powerful as a mainframe that is only a few years old. They range in size from one that you would set on, or under, your desk to one that you could hold in your hand. In addition, their processing support capacity ranges from one user to a dozen or more. As PCs continue to become more powerful and affordable, their use is moving into what was once the domain of the low-end minicomputer. At a minimum, they generally consist of at least a keyboard , a pointing device , a screen , and a system unit .