Classifications of Computers based on size.

Supercomputers

These are arguably the most powerful in terms of speed and accuracy. They are types of computers used in solving complex mathematical computations. They are capable of executing trillions of instructions per second, which is calculated in floating point operations per second (FLOPS).

These computers are the largest in terms of size. They can occupy anything from a few feet to hundreds of feet. They also don’t come cheap as they can be priced between $200,000 to over $100 million.

Mainframes

Mainframe computers are large-sized computer types. They are equally powerful but fall short in terms of the computation ability in supercomputers. They are like big file servers, enabling multiple users from nearby and remote locations to access resources at the same time. Also known as big iron, these systems can handle massive amounts of data going in and out simultaneously. This makes them popular with businesses.

They are also resilient, as they are capable of operating for over 10 years without failing.

The price of mainframe computers, especially from IBM, starts at $75,000 and can go up to $1 million.

Minicomputers

Minicomputers are general-purpose devices without the monumental expenses associated with a larger system. Their processing power is below that of mainframe systems but above the capabilities of personal computers.

Also known as mid-range computers, these became popular in the late 1960s but have become almost extinct because of the popularity of personal computers. The latter can now perform most of the tasks reserved for minis.

The first minicomputer was unveiled in 1967 by Digital Equipment Corporation and was followed later by designs from IBM and other companies.

Servers

These are types of computers used to provide resources, services, and functionality to client computers in a server-client network model. 

A common errant is that desktop systems can be used as servers. Far from it, true server systems are specialized computers with abilities far beyond what personal computers can deliver.

Servers are optimized to run for 24 hours and are capable of hot-swapping storage and other hardware without having to shut down the system.