According to the size and power computers are classified.
Super computers
Super computers are employed for heavy usage like construction of atom bombs, weather forecasting, finding oil, earthquake predictions, electronic design and scientific simulations. These computers are extremely faster that other computers currently available. They can perform hundreds of millions of commands per second.
Mainframe computers
Mainframe computers are very large, expensive and powerful multi-user computers. It supports up to hundreds of users simultaneously. It is build into a frame means all units were hung into a frame, therefore it is called mainframe computer. Banks, companies and universities use mainframe computers. Some features of this computer are given below.
Has 1 to 16 CPU's
Memory ranges from 128Mb over 8Gb on line RAM
Processing power ranges from 80 over 550 Mips
Has different cabinet for storage, I/O and RAM
Has separate processes for
Task management
Job management
Catalogs
Communication
Serialization
Inter address space
Mini computers
They are low cost and midsize computers. These computers are associated with de-centralized computing that most of computing tasks place on the mini itself. A mini computer can support up to 200 users simultaneously. So it is a multi processing system.
Workstations
These types of computers are used for desktop publishing, engineering applications, software development and other types of applications which required high quality graphics. UNIX and Windows NT operating systems are most commonly used in these computers. These types of computers are built in network support, contain large amount of RAM and a graphical user interface. Most workstation doesn't have a disk drive. These computers are used to form a local area network.
Personal computers
Personal computers are design for an individual user. They are low-cost and small in size. These are based on micro