Computer classification by the size

CLASSIFICATION BASED ON SIZE AND CAPABILITY

Classification digital Computer based on size and Capability
Based on size and capability, computers are broadly classified into

a.                   Microcomputers(Personal Computer)

 A microcomputer is the smallest general purpose processing system. The older pc started 8 bit processor with speed of 3.7MB and current pc 64 bit processor with speed  of 4.66 GB.
Examples: -     IBM PCs, APPLE computers

Microcomputer can be classified into 2 types :

1.       Desktops
2.       Portables
The difference is portables can be used while travelling whereas desktops computers cannot be carried around.

The different portable computers are: -

1)         Laptop
2)         Notebooks
3)         Palmtop (hand held)
4)         Wearable computers

Laptop: - this computer is similar to a desktop computers but the size is smaller. They are expensive than desktop. The weight of laptop is around 3 to 5 kg.

Notebook: - These computers are as powerful as desktop but size of these computers are comparatively smaller than laptop and desktop. They weigh 2 to 3 kg. They are more costly than laptop.

Palmtop (Hand held): - They are also called as personal Digital Assistant (PDA). These computers are small in size. They can be held in hands. It is capable of doing word processing, spreadsheets and hand writing recognition, game playing, faxing and paging. These computers are not as powerful as desktop computers. Ex: - 3com palmV.

Wearable computer: - The size of this computer is very small so that it can be worn on the body. It has smaller processing power. It is used in the field of medicine. For example pace maker to correct the heart beats. Insulin meter to find the levels of insulin in the blood.

b).    Workstations:- It is used in large, high-resolution graphics screen built in network support, Engineering applications(CAD/CAM), software development desktop publishing

Ex: Unix and windows NT.

b)         Minicomputer: -   

      A minicomputer is a medium-sized computer. That is more powerful than a microcomputer. These computers are usually designed to serve multiple users simultaneously (Parallel Processing). They are more expensive than microcomputers.

            Examples:        Digital Alpha, Sun Ultra.

c)         Mainframe computers: - 

Computers with large storage capacities and very high speed of processing (compared to mini- or microcomputers) are known as mainframe computers. They support a large number of terminals for simultaneous use by a number of users like ATM transactions. They are also used as central host computers in distributed data processing system.

            Examples: -     IBM 370, S/390.

d) super comptuers :-

     Supercomputers have extremely large storage capacity and computing speeds which are many times faster than other computers. A supercomputer is measured in terms of tens of millions Instructions per second (mips), an operation is made up of numerous instructions. The supercomputer is mainly used for large scale numerical problems in scientific and engineering disciplines such as Weather analysis.

            Examples: -     IBM Deep Blue

Five generations of computers

The five generations of computers

Computers are such an integral part of our everyday life now most people take them and what they have added to life totally for granted. Even more so the generation who have grown from infancy within the global desktop and laptop revolution since the 1980s.

The history of the computer goes back several decades however and there are five definable generations of computers. Each generation is defined by a significant technological development that changes fundamentally how computers operate – leading to more compact, less expensive, but more powerful, efficient and robust machines.

1940 – 1956:  First Generation – Vacuum Tubes

These early computers used vacuum tubes as circuitry and magnetic drums for memory. As a result they were enormous, literally taking up entire rooms and costing a fortune to run. These were inefficient materials which generated a lot of heat, sucked huge electricity and subsequently generated a lot of heat which caused ongoing breakdowns.

These first generation computers relied on ‘machine language’ (which is the most basic programming language that can be understood by computers). These computers were limited to solving one problem at a time. Input was based on punched cards and paper tape. Output came out on print-outs. The two notable machines of this era were the UNIVAC and ENIAC machines – the UNIVAC is the first every commercial computer which was purchased in 1951 by a business – the US Census Bureau.

1956 – 1963: Second Generation – Transistors

The replacement of vacuum tubes by transistors saw the advent of the second generation of computing. Although first invented in 1947, transistors weren’t used significantly in computers until the end of the 1950s. They were a big improvement over the vacuum tube, despite still subjecting computers to damaging levels of heat. However they were hugely superior to the vacuum tubes, making computers smaller, faster, cheaper and less heavy on electricity use. They still relied on punched card for input/printouts.

The language evolved from cryptic binary language to symbolic (‘assembly’) languages. This meant programmers could create instructions in words. About the same time high level programming languages were being developed (early versions of COBOL and FORTRAN). Transistor-driven machines were the first computers to store instructions into their memories – moving from magnetic drum to magnetic core ‘technology’. The early versions of these machines were developed for the atomic energy industry.

1964 – 1971: Third Generation – Integrated Circuits

By this phase, transistors were now being miniaturised and put on silicon chips (called semiconductors). This led to a massive increase in speed and efficiency of these machines.  These were the first computers where users interacted using keyboards and monitors which interfaced with an operating system, a significant leap up from the punch cards and printouts. This enabled these machines to run several applications at once using a central program which functioned to monitor memory.

As a result of these advances which again made machines cheaper and smaller, a new mass market of users emerged during the ‘60s.

1972 – 2010: Fourth Generation – Microprocessors

This revolution can be summed in one word: Intel. The chip-maker developed the Intel 4004 chip in 1971, which positioned all computer components (CPU, memory, input/output controls) onto a single chip. What filled a room in the 1940s now fit in the palm of the hand. The Intel chip housed thousands of integrated circuits. The year 1981 saw the first ever computer (IBM) specifically designed for home use and 1984 saw the MacIntosh introduced by Apple. Microprocessors even moved beyond the realm of computers and into an increasing number of everyday products.

The increased power of these small computers meant they could be linked, creating networks. Which ultimately led to the development, birth and rapid evolution of the Internet. Other major advances during this period have been the Graphical user interface (GUI), the mouse and more recently the astounding advances in lap-top capability and hand-held devices.

2010-  : Fifth Generation – Artificial Intelligence

Computer devices with artificial intelligence are still in development, but some of these technologies are beginning to emerge and be used such as voice recognition. AI is a reality made possible by using parallel processing and superconductors. Leaning to the future, computers will be radically transformed again by quantum computation, molecular and nano technology.  The essence of fifth generation will be using these technologies to ultimately create machines which can process and respond to natural language, and have capability to learn and organise themselves.

Computer classification by purpose

CLASSIFICATIONS OF COMPUTERS BY PURPOSE

Digital computers may be utilized for either special or general purposes.

1. General-Purpose Computers

 This machines have the capability of dealing with variety of different problems, and are able to act in response to programs created to meet different needs. A general-purpose computer is one that has the ability to store different programs of instruction and thus to perform a variety of operations.

2. Special-Purpose Computers

 as to the name implies, is designed to perform one specific tasks. The program of instructions is built into, or permanently stored in the machine. Specialization results in the given task being preformed very quickly and efficiently. Most special purpose computers have the capability of performing just one task. They are frequently referred to us "dedicated," because of their limitations to the ?
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Definition for computer systems

Definition for computer systems

The complete computer made up of the CPU, memory and related electronics (main cabinet), all the peripheral devices connected to it and its operating system. Computer systems fall into two categories: clients and servers.

Clients are the user's laptop, desktop and tablet computers and smartphones, while servers share their data and applications with multiple users. Servers range from entry-level rack mounts to mainframes. See rack mounted and mainframe.

A computer system is sized for the number of users it handles simultaneously, the type of work performed (office, engineering, etc.) and the volume of data that must be stored.

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