Digital computers are classified according to sizes, speed and memory capacity. Digital computers are of different types:
- Super Computer
- Mainframe computer
- Mini computer
- Micro computer
Supercomputer are very fast computers that can perform hundreds of millions of instructions per second. These are the fastest calculating devices. These computers are used by government agencies. A supercomputer is typically used for scientific and engineering applications that must handle very large databases or do a great amount of computation (or both).
At any given time, there are usually a few well-publicized supercomputers that operate at extremely high speeds. Supercomputers are really multiple computers that perform parallel processing.
- IBM’s Roadrunner is the fastest supercomputer in the world, twice as fast as Blue Gene and six times as fast as any of the other current supercomputers. At the lower end of supercomputing, a new trend called clustering, takes more of a build-it-yourself approach to supercomputing.
- The best-known builder of supercomputers has been Cray REsuearch, now a part o Silicon Graphics. in September 2008, Cray and Microsoft launched CXI, a $25,000 personal supercomputer aimed markets such as aerospace, automotive, academic, financial services and life sciences.
- Some scientific problems and processes are so complex that you need super computers to tackle them.
- Climate researchers model Earth’s current and predicted future climate using supercomputers.
- Astronomers and space scientists use supercomputers to study the Sun and space weather.
- Scientists use supercomputers to simulate how a tsunami would impact a coastline or a given city.
- Supercomputers are used to simulate supernova a explosions in space.
- Supercomputers are used to test the aerodynamics of the latest military planes.
- Supercomputers are being used to model how proteins fold and how that folding might affect people that have Alzheimer’s Disease, Cystic Fibrosis and many kinds of cancer.
- Supercomputers are used to model nuclear explosions, limiting the need for real nuclear testing.
Mainframe is an industry term for a large computer. The name comes from the way the machine is build into a frame, therefore it is called Mainframe. Because of the high development costs, mainframes are typically manufactured by large companies such as IBM, Amdahl, Hitachi.
Uses of the Mainframe computers
Mainframe computers are used to run commercial applications and other large scale computing purpose. It is also used in banking and insurance businesses where enormous amounts of data are processed, typically (at least) millions of records, each day.
Minicomputers are introduced in the early 1960’s and announced a new era in computing. They are relatively low cost an small. This setup allowed more people to have access to computers and as result an era of new applications in universities, industry, and commerce are created. Digital Equipment Corporation developed the PDP-8 virtually conquered the market is a sweep and sold over 40,000 units. In time some 200 companies produced this type of minicomputers. DEC got at the top of the market with the PDP-11, and with the VAX 11/780 system. The latter will become a landmark system in the history of computing.
Uses of the Mini Computer
- They offer a limited range of peripherals.
- Limited software can be used.
- There is facility for direct operation of the machine by the end user.
- Air conditioning is not necessary for minicomputers.
The Micro / Personal Computers
The term “Microcomputer” came into popular used after the introduction of the minicomputer. The earliest models often sold as kits to be assembled by the user, and came with as little as 256 bytes of RAM, and no input/output devices other than indicator lights and switches, useful as a proof of concept to demonstrate what such a simple device could do.
However, as microprocessors and semiconductor memory became less expensive, microcomputers in turn grew cheaper and easier to use.
Increasingly inexpensive logic chips such as the 7400 series allowed cheap dedicated circuitry for improved user interfaces such as keyboard input, instead of simply a row of switches to toggle bits one at a time.
These computers are used nowadays commonly and these computers revolutionized the computers industry because of their size and cost. Some of the features are following:
Cheap and easy to use:
Micro computers are cheap and easy to use.
Limited support for I/O Devices:
They support very limited input and input capacities.
They have less storage capacity.
These computers support very limited number of software.
Most of microcomputers are self-contained units, which are light enough and can be moved easily.
Number of operators:
They are designed to be used by one person at a time.
In addition to the CPU (Central Processing Unit), a microcomputer has an operator keyboard for input.
Hard disk and floppy disk drivers are used to enter and store data and programs.
A visual display screen and / or a printer is used to get the output.
Uses of Microcomputers
These are the most sold computer in the world. They are used for various applications ranging from business to engineering designs. They are also used by million of person all over the world for entertainment and personal applications.
The types of microcomputers are following:
- Desktop Computers
- Laptop Computers
- Palmtop Computers
Today the desktop computers are those computers which have the different desktop computer cases that can be laid on the desk and they are different from the tower computers on the basis of the design of the case as in towwer computers the CPU stand straight. And today the desktop computers have different monitors and the keyboard systems as compare to the earlier computers which have all the systems combined with each other. There are various such computers available like AMD desktop computer.
A Laptop is a personal computer signed for mobile use. It is small and light enough to sit on a person’s lap while in use. A laptop integrates most of the typical components of a desktop computer, including a display, a keyboard, a pointing device (a touchpad, also known as track pad, and/or a pointing stick), speakers, and often including a battery, into a single small and light unit. The rechargeable battery (if present) is charged from an AC adapter and typically stores enough energy to run the laptop for two to three hours in its initial state, depending on the configuration and power management of the computer.
A computer small enough to hold in one hand and operate with the other. Also called a “handtop”, these ultra-small computers may have specialized keyboards or keypads for data entry applications or have small qwerty keyboards.
Because of their small size, most palmtop computers do not include disk drives. However, many contain PCMCIA (Personal Computer Memory Card International Association) slots in which you can insert disk drives, modern, memory, and other devices.