- A computer system in contemporary usage refers to a desktop system, including the computer itself (aka "The CPU" or "The Box") and all the peripheral devices needed to operate it, usually including:
- The computer, usually mounted in a tower (vertical) case, including components: the CPU or central processing unit; a mother board or mainboard, including a BIOS; A graphics card; a sound card (often build onboard, ie. into the mainboard), a variety of disk ports to serve hard drives, disk drives and optical drives, a variety of peripheral ports, including USB ports, legacy serial and parallel ports, legacy psx, and SCSI; and LAN ports, either ethernet or firewire. A hard drive (sometimes more) is included for long-term data storage. The case also contains a transformer power supply and a number of fans to keep the internal components cool while operating.
- A monitor, typically either a CRT or an LCD flatscreen.
- A set of speakers to hear sound.
- A keyboard, typically a standard 104-key QWERTY keyboard.
- A mouse, typically a three button mouse with scroll wheel.
Other peripherals can be added to the system to augment its functionality. Common ones include:
- A wi-fi adapter to connect to wireless networks.
- A bluetooth adapter to connect to wireless peripherals.
- A modem for a direct connection to an internet service provider.
- A printer to produce (paper) hardcopy
- A scanner to input data from hardcopy
all these pieces, pulled together comprise a personal computer system.
Read more: http://wiki.answers.com/Q/What_is_a_computer_system#ixzz22ubFqhnx
ii) How does computer works?
- CPU:
This is the CPU stands for "Central Processing Unit" this is the brain to the computer. This is why you can running diffrent programs at the same time. If you press "CTRL+ALT+DEL" you can take a look at the CPU. The jobb to the CPU is to run programs you want the computer to run. When you click on a program the RAM are getting the data to the CPU.
- RAM:
This is the RAM stands for "Random Access Memory" this function work is to give the data to the CPU so the it can run a program. If you have alot of RAM you start up the programs faster since they send more information faster to the CPU.
How do we comunitcate with the computer?
Only way we can comunicate with the computer is with a "Keybored" and "mouse". Without the mouse and keybored we could't do any tasks on the computer. When we do a task on the computer we can see it on the screen so displayed on the computer. So the Screen is the output and input is the "keybored" and "mouse"
- AMU:
This is the Hard drive of the computer it stands for Auxiliary Memory Units. This is why you can store data on your computer if this did't exist you could't store anything at the computer. This can be called your root of the computer "C:"
- Secondary AMU's:
This will go under the name CD room, Floopy disks, CD, This can be called secondary storage places on the computer. This are normaly used to copy important information on so you don't want to los. Why should i make a copy of important information? Well sometimes things can happend to the computer like the Auxiliary Memory Unit Crash. This will say that the hard disk wont boot up. or mabye you get Virus infection so is destroying your computer.
iii) What is computer network?
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Computer Networks
Networks are collections of computers, software, and hardware that are all connected to help their users work together. A network connects computers by means of cabling systems, specialized software, and devices that manage data traffic. A network enables users to share files and resources, such as printers, as well as send messages electronically (e-mail) to each other.
Computer networks fall into two main types: client/server networks and peer-to-peer networks. A client/server network uses one or more dedicated machines (the server) to share the files, printers, and applications. A peer-to-peer network allows any user to share files with any other user and doesn’t require a central, dedicated server.
The most common networks are Local Area Networks or LANs for short. A LAN connects computers within a single geographical location, such as one office building, office suite, or home. By contrast,Wide Area Networks (WANs) span different cities or even countries, using phone lines or satellite links.
Networks are often categorized in other ways, too. You can refer to a network by what sort of circuit boards the computers use to link to each other – Ethernet and Token-Ring are the most popular choices. You can also refer to a network by how it packages data for transmission across the cable, with terms such as TCP/IP (Transmission Control Protocol/Internet Protocol) and IPX/SPX (Internet Package eXchnage/Sequenced Package eXchange).
iv) Computer history and generations
Computer History
Computer Generations
- First Generation (1940-1956) Vacuum Tubes
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The first computers used vacuum tubes for circuitry and magnetic drums formemory, and were often enormous, taking up entire rooms. They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions.
First generation computers relied on machine language, the lowest-level programming language understood by computers, to perform operations, and they could only solve one problem at a time. Input was based on punched cards and paper tape, and output was displayed on printouts.
The UNIVAC and ENIAC computers are examples of first-generation computing devices. The UNIVAC was the first commercial computer delivered to a business client, the U.S. Census Bureau in 1951.
- Second Generation (1956-1963) Transistors
Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages, which allowed programmers to specify instructions in words. High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN. These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.
The first computers of this generation were developed for the atomic energy industry.
- Third Generation (1964-1971) Integrated Circuits
The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.
Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitorsand interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory. Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors.
- Fourth Generation (1971-Present) Microprocessors
The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room could now fit in the palm of the hand. The Intel 4004 chip, developed in 1971, located all the components of the computer—from the central processing unit and memory to input/output controls—on a single chip.
In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh. Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use microprocessors.
As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUIs, the mouse and handhelddevices.
- Fifth Generation (Present and Beyond) Artificial Intelligence
v) Classification of computer
- Analog Computer
An analog computer (spelt analogue in British English) is a form of computer that uses continuous physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved
Digital Computer
A computer that performs calculations and logical operations with quantities represented as digits, usually in the binary number system
Hybrid Computer (Analog + Digital)
A combination of computers those are capable of inputting and outputting in both digital and analog signals. A hybrid computer system setup offers a cost effective method of performing complex simulations.
On the basis of Size
Super Computer
The fastest and most powerful type of computer Supercomputers are very expensive and are employed for specialized applications that require immense amounts of mathematical calculations. For example, weather forecasting requires a supercomputer. Other uses of supercomputers include animated graphics, fluid dynamic calculations, nuclear energy research, and petroleum exploration.
The chief difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs concurrently.
Mainframe Computer
A very large and expensive computer capable of supporting hundreds, or even thousands, of users simultaneously. In the hierarchy that starts with a simple microprocessor (in watches, for example) at the bottom and moves to supercomputers at the top, mainframes are just below supercomputers. In some ways, mainframes are more powerful than supercomputers because they support more simultaneous programs. But supercomputers can execute a single program faster than a mainframe.
Mini Computer
A midsized computer. In size and power, minicomputers lie between workstations and mainframes. In the past decade, the distinction between large minicomputers and small mainframes has blurred, however, as has the distinction between small minicomputers and workstations. But in general, a minicomputer is a multiprocessing system capable of supporting from 4 to about 200 users simultaneously.
Micro Computer or Personal Computer
Desktop Computer: a personal or micro-mini computer sufficient to fit on a desk.
Laptop Computer: a portable computer complete with an integrated screen and keyboard. It is generally smaller in size than a desktop computer and larger than a notebook computer.
Palmtop Computer/Digital Diary /Notebook /PDAs: a hand-sized computer. Palmtops have no keyboard but the screen serves both as an input and output device.
Workstations
A terminal or desktop computer in a network. In this context, workstation is just a generic term for a user's machine (client machine) in contrast to a "server" or "mainframe."
vi) Computer Components
- Computers are made of the following basic components:
- Case with hardware inside:
- Power Supply - The power supply comes with the case, but this component is mentioned separately since there are various types of power supplies. The one you should get depends on the requirements of your system. This will be discussed in more detail later
- Motherboard - This is where the core components of your computer reside which are listed below. Also the support cards for video, sound, networking and more are mounted into this board.
- Microprocessor - This is the brain of your computer. It performs commands and instructions and controls the operation of the computer.
- Memory - The RAM in your system is mounted on the motherboard. This is memory that must be powered on to retain its contents.
- Drive controllers - The drive controllers control the interface of your system to your hard drives. The controllers let your hard drives work by controlling their operation. On most systems, they are included on the motherboard, however you may add additional controllers for faster or other types of drives.
- Hard disk drive(s) - This is where your files are permanently stored on your computer. Also, normally, your operating system is installed here.
- CD-ROM drive(s) - This is normally a read only drive where files are permanently stored. There are now read/write CD-ROM drives that use special software to allow users to read from and write to these drives.
- Floppy drive(s) - A floppy is a small disk storage device that today typically has about 1.4 Megabytes of memory capacity.
- Other possible file storage devices include DVD devices, Tape backup devices, and some others.
- Monitor - This device which operates like a TV set lets the user see how the computer is responding to their commands.
- Keyboard - This is where the user enters text commands into the computer.
- Mouse - A point and click interface for entering commands which works well in graphical environments.
