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SuperComputers

Supercomputers are the most powerful computers made and physically they some of the largest. These systems are built to process huge amount of data and the faster supercomputers can perform more than 1 trillion calculations per second. some supercomputers - such as the Cray'T90 system -can house thousands of processors. This speed and power make supercomputers ideal for handling large and highly complex problems that require extreme calculating power.

Scientist and engineers frequently build models of complex processes, then simulate the processes on a supercomputer. These computers help analyze and forecast global weather patterns, for example, while shedding light on related issues such as pollution, global warming and the depletion of the earth's ozone layer. Nuclear scientist use supercomputers to create and analyze models of nuclear fission and fusion, predicting the actions and reactions of millions of atoms as they interact.

Supercomputers are also being used to map the human genome, or DNA structure. The Human Genome project, for example, uses supercomputing resources around the world in the hope of discovering all the human genes. scientist estimate there are from 80,000 to 100,000 human genes, made up of more than 3 billion chemical bases. If printed, th ehuman DNA sequence would fill about 200,000pages.

Supercomputers can cost tens of millions of dollars and consume enough electricity to power dozens of homes. They are often housed in protective rooms with special cooling systems, power protection, and other security features . Because of their size and cost , supercomputers are relatively used only by large corporations, universities and government agencies that can afford them. Supercomputing resources are often shared to give researchers access to these precious machines.

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The types of computer

Computers come in many different sizes and ranges of power and different types of computer systems have varying capabilities. Basically , today's computer system fall into one of the following categories.

1.Supercomputers.
2.Mainframe computers
3.Minicomputers or mid range computers
4.Workstations
5.Microcomputers or personal computers

All of these computers can be connected to form networks of computers, but each individual computer, whether or not it is on a network, falls into one of these categories - especially microcomputers can be divided into subcategories, some of which are growing  rapidly enough to become major categories in their own right.

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Operating system

When you turn on computer, it goes through several steps to prepare itself for use. the first is called  the Power on self test(POST). The computer identifies the devices attached to it, identifies the amount of memory available and does quick check to see whether the memory is functioning properly. This routine  is initiated by a part of the system software located in read-only memory(ROM), a chip that contains brief, permanent instructions for starting the computer.

Next, the computer looks for an operating system, which is usually stored in the hard disk. The operating system tells the computer how to interact with the user and how to use devices such as the disk drives, keyword, and monitor. When it finds the operations, the computer loads a portion of it into memory. Because the operating system is necessary for controlling the computers most basic functions, it continues to run until the computer is turned off.

After the computer finds and runs the operating system, it is ready to accept commands from an input device - usually the keyboard or a mouse - or from a program. At this point , the user can issue commands to the computer. A command might , for example, list the programs stored on the computers disk or make the computer run one of those programs.

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Storage in Computer

A computer can function with only processing , memory, input and output devices. To be really useful, however, it also needs a place to keep program files and related data when it is not using them. The purpose of storage is to hold data. 

Think of storage as an electronic file cabinet and RAM as an electronic workable. when you need to work with a program or a set of data, the computer locate it in the file cabinet and puts a copy on the table. After you have finished working with the proram or data, you put it back into the file cabinet. If you make changes to data while working on it, the changed data replaces the original data in the file cabinet .

There are three major distinctions between storage and memory:

1. There is more room in storage than in memory , just as there is more room in a file cabinet than there is on a tabletop.

2. Contents are retained in storage when the computer is turned off, whereas the programs or the data you put into memory disappear when you shutdown the computer.

3. Storage is very slow compared to memory, but it much cheaper than memory.

Remember the distinction between storage and memory. Their functions are similar, but they work in different ways. Novice computer users often use the term memory when they actually mean storage or disk. This mistake can cause confusion.

The most common storage medium is the magnetic disk. A disk is a round, flat object that spins around its center. Read/write heads, which are similar to the heads of a tape recorder or VCR, are used to read data from the disk or write data onto the disk, Depending on the type of disk , the read/write heads may float just above the disk's surface or may actually touch the disk.

The device that holds a disk is called disk drive. Some disks are built into the drive and are not meant to be removed ; other kinds of drives enable you to remove  and replace disks. Most personal computers have at least one non removable hard disk. In addition, there is also a diskette drive, which allows you to use removable disk or hard drive. In addition , there is also a diskette drive, which allows you to use removable diskettes. A hard disk can store far more data than a diskette can, so the hard disk serves as the computer's primary filing cabinet. Diskettes are used to load new programs or data onto the hard disk , trade data with other users , and make backup copies of the data on the hard disk.

Because you can remove diskettes from a computer from a computer, they are encased in a plastic or vinylcover to protect them from fingerprints and dust. Because the cover used in early diskettes was thin, the diskette was flimsy or "floppy" as a result they came to be called floppy disk.

The CD - ROM drive is the most common type of storage device after the hard and diskette drives . Compact disks are a type of optical storage device, identical to audio. CDs, that can store about 74 minutes of audio or 650 MB of data, or about 450 times as much information as a diskette. The type used in computers is called Compact Disk Read - Only Memory (CD-ROM). The name implies that you cannot change information on the disk, just as you cannot record over an audio CD.

If you purchase a CD-Recordable (CD-R) drive, you have the option of creating your own CDs. A CD-R drive can write data to and read data from compact disk. To use CD-Drive, you must use a special CD-R disk, which can be written on only once, or a CD- Rewrite-able (CD-RW)disk, which can be written to multiple times, like a floppy disk.

                                                                  CD - Recordable

An increasingly popular storage technology is the digital versatile disk or  Digital Video Disk (DVD) , which is revolutionizing home entertainment. Using sophisticated compression technologies, a single DVD which is the same size as a standard compact disk can store an entire fill length movie. DVDs can hold a minimum of 4.7GB of data and as much as 17GB. Future DVD technologies promise much higher storage capacities on a  single disk. DVD drives  can also locate data on the disk much faster than standard CD-ROM drives.

DVDs require  a special player. The new players, however, can play audio, data and DVD disks, freeing the user from the necessity of purchasing different players for each type of disk. DVD drives are now standard  equipment on many new personal computers. Users not only install programs and data from their standard CDs , but they can also watch movies on their PC's by using a DVD.

                                                                              DVD

Other types of storage devices include tape drives, optical drives, removable hard drives, and many others.

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Input and output devices

Computers would be useless if they did not provide interaction with users, they could not receive instructions or deliver the results if their work. Input devices accept data and instructions from the user or from another computer system such as computer on the Internet.Output devices return processed data back to the user or to another computer system.The most common input device is the keyboard, which accepts letters, numbers, and commands from the user. Another popular input device is the Mouse , which less you select options from on-screen menus. You use a mouse by moving it across a flat surface and pressing its buttons. Other popular input devices are trackballs, touch pads, joysticks, scanners, digital cameras and microphones.


The mouse , trackball and touch pad enable you to draw a point or the screen. The joystick is especially well suited for playing fast - moving video games. A scanner can copy a printed page of text or a graphic into the computer's memory, eliminating the time - consuming step of typing input or creating an image from scratch. Digital cameras record live images that can be viewed and edited on the computer. A microphone or CD player attached to the computer enables you to add the sound of a voice or a music selection.

The function of an output device is present processed data to the user. The most common output devices are the display screen, known as the monitor, and the printer. The computer sends output to the monitor when the user needs only to see the output. It sends output to the printer when the user needs a paper copy also called a " hard copy", Just as computers can accept sound as input, they can use stereo speakers or headphones as output devices to produce sound.

Some types of hardware can act as both input and output devices. One example is the Touch screen, a type of monitor that display text or icons you can touch. Touch  screens are popular in museums and libraries, where they help direct people to specific areas. In bookstores and music stores, touch screens enable customers to locate an item quickly  without wandering the aisles or searching through card catalogs. Touch screens are even used in gambling casinos, where they provide a fun and non mechanical interface to slot machines.when you touch the screen, special sensors detect the touch, then the computer calculates the point on the screen where you placed your finger. Depending on the location of the touch, the computer responds by displaying new data.

The most common types of devices that can perform both input and output are communication devices, which connect one computer to another - a process known as networking. among the many kinds of communication devices, the most common are moderns, which enable computers to communicate through telephone lines or cable television systems and network interface cards (NICs), which let users connect a group of computers to share data and devices.

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Memory

Memory is like an  electronic scratch  pad inside the computer. When you launch a program , it is loaded into run from memory, Data used by the program is also loaded into memory for fast access.  As you enter new data into computer, it is also stored in memory - but only temporarily. the most common type of memory is called random access memory, or RAM. As a result , the term memory is commonly used to mean RAM. It is also sometimes called read/write memory. Data is both written to and read from this memory. Perhaps the most important thing to remember about RAM is that it is volatile, so it needs a constant supply of power. when you turn off a computer , everything in RAM disappears. as you will soon learn this why you frequently have to save your data files to a storage device.

One of the most important factors affecting the speed and power of a computer is the amount of  RAM  it has . Generally , the more RAM a computer has, the more it can do and the faster it can perform certain tasks. The most common measurement unit for describing a computer's memory is the alphabet or a numeral. when people talk about memory, the numbers are often so large that it is useful to use terms such as kilobyte, megabyte, gigabyte and terabyte to describe the value.

Todays personal computers commonly have from 64 to 128 million bytes of memory. Newer system seldom have less than 64MB. Newer generations of PC's feature more RAM than previous generations did because newer versions of operationg systems and application software require ever increasing amounts of RAM to operate efficiently. Adding RAM is a relatively inexpensive way to boost a system's overall  performance. As a rule of thumb, the more RAM a computer has, the better. Note, too , that it is usually possible to add more RAM to a standard computer; some newer systems can be upgraded to nearly 1 GB of RAM. .

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Looking Inside The machine

The computer hardware - the hardware - has many parts , but the critical components fall into one of four categories.

1. Processor.

2. Memory.

3. Input and out put devices.

4. Storage.

The Processor that transforms raw data into useful information is called Processing. To perform this transformation, the computer users two components: the processor and memory.

The processor is like the brain of  the computer in the way that it organizes and carries out instructions that come from either the user or the software . In a personal computer, the processor usually consists of one or more microprocessors sometimes called "chips". which are silvers of silicon or other material etched with many tiny electronic circuits. To process data, the computer passes electricity through the circuits to complete 

an instruction.

The processor is plugged into the computer's mother board. The motherboard is a rigid rectangular card containing the circuitry that connects the processor to the other hardware. The motherboard is an example of a circuit board. In most personal computers, many internal devices- such as video cards, sound cards, disk controllers, and other devices - are housed on their own smaller circuit boards - which attach to the motherboard. Newer microprocessors are large and complex enough to require their own dedicated circuit boards, which plug into a special slot in the motherboard , You can think of the mother board as the master circuit board in a computer. Note , however , that in newer personal computers, some devices are built directly onto the motherboard instead of  attaching to it as a separate circuit board. This development promises to make computers smaller, faster, and less expensive.

A personal computer's processor is usually a single chip or a set of chips contained on a circuit board. In some powerful computers, the processor consists of many chips and the circuit boards on which they are mounted. In either case. the term central processing unit (CPU) refers to a computer's processor. People often refer to computer system by the type CPU they contain. A Pentium system, for example uses Pentium class microprocessor as its CPU.

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The Parts of a Computer System

In general terms computer is an electronic device used to process data, converting the data into information that is useful to people . Any computer -regardless of its type - is controlled by programmed instructions, which give the machine a purpose and tell it what to do.

Computers come in many varieties , including  the personal computer, tinny computers built into appliances and automobiles, and mainframe machines used by many people simultaneously to run a business. despite their differences in size and use, all these computers are part of a system. A complete computer system consists of  four parts: hardware, software, people and data.

The Mechanical devices that make up the computer are called hardware. In other words, hardware is any part of the computer you can touch. Hardware consists of inter connected electronic devices that you can
use to control the computer's operation, input and out put. The generic term refers to any piece of hardware.

Software is a set of electronic instructions consisting of complex codes also know an programs that make the computer perform tasks. In other words, software tells the computer what to do. some programs exist primarily for the computers use and help the computer perform and manage its own tasks. Other types of programs exist primarily for the user and enable the computer to perform tasks, such as creating documents or drawing pictures.

People are the computer operators also know as users. It can be argued that some computer systems are complete without a persons involvement; however no computer is totally autonomous. Even if a computer can do its job without a person sitting in front of it, People still design, build, program and repair computer systems. This lack of autonomy is especially true of personal computer systems, which are the focus of this book and which are designed specifically for use by people.

Data consists of raw facts, which the computer stores and reads in the form of numbers, the computer manipulates data according to the instructions contained in the software and then forwards it for use by people or another computer. Data can consist of letters, numbers, sounds or images. No matter what kind if data is entered into a computer, how ever the computer converts it to numbers. Consequently, computerized data is digital , meaning that it has been reduced to digits, or numbers.

within the computer, data is organized into files. A computer file is simply a set of data or program instructions that has been given a name. A file that the user can open and use is often called a Document. Although many people think of documents simply as text, a computer document can include many kinds of data. For example a computer document can be a text, a group of numbers or any combination of these items. Programs are oraganized into files as well, but because programs are not considered data, they are not document files.

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Over View of computer system

Have you ever watched an incredible scene in a movie, or seen a drawing  that looked  so realistic yu thought it was a photograph? Afterward, were you amazed to learn that it was done on a computer? If so you are certainly not alone. we are endlessly surprised by the feats accomplished with the help of computers and marvel at their complexity. For this reason, many people assume that computers must be difficult to understand and difficult t use. Most of us do not realize, how ever that computers are basically simple devices, and all computers have a great deal in common. Most computers from biggest to the smallest  operate on the same fundamental principles. They are all fabricated from the same basic types of components, and they all need instructions to make them run.

             As a first step toward understanding and learning to use computers, this lesson gives you a peek at these fascinating machines. you will learn about the types of hardware that all computersystems, and the types of software that make them run. you will also see that without a user - some onelike you - a computer system is not really complete.

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