I. Range (1 - 7) the following statements (a-g) according to the order they appear in the text.
1. Anti-virus programs are used to detect and remove viruses.
2. CD-ROMs are storage devices that use laser light for reading and writing data.
3. The connection of networks throughout the world is known as the Internet.
4. Personal computers include desktop computers and handheld computers that can be carried around by the user.
5. A special set of programs, called an operating system, provides an interface for the user and allows applications programs to communicate with the hardware.
6. The Web contains interlinked documents called webpages.
7. An Internet system designed to provide free, interactive access to vast resources for people all over the world is sometimes referred to as an information superhighway.
II. Match the words and their definitions.
| computer | computer designed for use by one person at a time |
| hardware | devices, that can be added externally to a computer |
| software | communication service, available on the Internet, that is used for sending and receiving text messages |
| operating system | electronic circuit boards that can be plugged into special sockets called expansion slots |
| viruses | a special set of programs, that provides an interface for the user and allows applications programs to communicate with the hardware |
| personal computers | a set of related webpages stored together on a server computer |
| expansion cards | moving from webpage to webpage using a Web browser program |
| peripherals | device that processes data according to a set of instructions known as a program. |
| special programs, designed to allow the user to find relevant webpages on the Web | |
| downloading | the equipment |
| website | copying data from a larger server system to a client |
| search engines | the programs and data |
| browsing | harmful programs that can reproduce themselves and attach themselves to other programs |
ІІІ. Decide whether the following statements are true (T) or false (F).
1. A special program designed for building spreadsheets and calculating mathematical formulae with is called word processor.
2. Keyboard is an outputting device.
3. Computers that can be carried around by the user are called desktop computers.
4. A multimedia computer can process different forms of data including text, graphics, audio, animation and video.
5. A combination of education and entertainment is sometimes referred to as edutainment.
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6. Copying data from a larger server system to a client is referred to as uploading.
7. An Internet system is sometimes referred to as an information superhighway.
8. Email attachments are the files attached to simple email text messages.
9. Hard disk looks like a set of aluminium disks coated in a magnetic material and enclosed in a vacuum-sealed case.
IV. Reading the text.
Computer Architecture
There are different types of computer of varying size and power, including the following:
Supercomputer(the most powerful type of mainframe) Mainframe(large, very powerful, multi-useri.e. can be used by many people at the same time, multi-taskingi.e. can run many programs and process different sets of data at the same time) Minicomputer(smaller than a mainframe, powerful, multi-user, multi-tasking). Personal computer (PC)(single user) Desktop computer(suitable size for sitting on an office desk) Workstation(most powerful type of desktop, used for graphic design, etc.) Portable(can be carried around, can operate with batteries) Laptop(large portable, can be rested on user’s lap) Notebook(size of a sheet of notebook paper) Handheld(can be held in one hand) Pen-based(main input device is an electronic pen) PDA(personal digital assistant, has functions such as task lists, diary, address book).
Note that the term PCusually refers to an IBM compatible personal computer i.e. an Apple Mac personal computer is not referred to as a PC. A computer that provides a service on a network e.g. storing files, sharing a printer, is known as a servercomputer. Server computers usually have a UPS(uninterruptible power supply) attached to them. This is a battery that automatically provides an electricity supply to allow the server to shut it self down properly if the main supply fails. The processore.g. Pentium, is the most important part of the computer. It processes the data and controls the computer. Powerful computers used as servers often have more than one processor. There are two main types of memory:
a) RAM(random access memory) holds the program instructions and the data that is being used by the processor,
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b) ROM(read only memory) holds the program instructions and settings required to start up the computer.
The combination of the processor and memory is sometimes referred to as the CPU (central processing unit), although sometimes the processor itself is referred to as the CPU. The other parts connected to the CPU are known as peripherals.These can include input devices, output devices, storage devices and communications devices. Input devicesinclude: keyboards, scanners, barcode readers, digital cameras, microphones and video cameras e.g. webcams (small digital video cameras used on the Web). Output devicesinclude: monitors(VDU display screens), printers, plotters, loudspeakers and headphones. Storage devicesinclude: magnetic tape, floppy disks(diskettes), hard disks, CD-ROMs, CD-R disks, CD-RW disks, DVDs and MO disks. A common communications deviceis a modem(a modulator/demodulator used for converting digital signals to analogue signals and vice versa to allow a computer to be connected to the ordinary telephone system).
A set of connectors used for carrying signals between the different parts of a computer is known as a bus.Data is transferred constantly between the processor and memory along the system bus.Each part of memory has its own memory addressand the processor determines where processed data is stored by sending an address signal along an address busand data along a databus. This is synchronized by an electronic clock in the CPU that determines the operating speed of the processor. Transferring data between the processor and RAM can slow up the computer; therefore, some very expensive, extremely fast memory is usually used as a cacheto hold the most frequently used data.
In a desktop computer, the CPU(central processing unit) and storage devices(pieces of equipment used for reading from and writing to a storage medium) are normally built inside a system unitwhich consists of a metal chassis enclosed in a flat desktop or a tower shaped case. Other peripherals are attached to the system unit by cables. Each peripheral uses its own driver cardor controller(an expansion card that is plugged into special expansion slotsin the system unit). Expansion cardscontain the electronics required to communicate with and control the device e.g. videoor graphics cardsare used for monitors, soundcardsare used for audio input/output and NICs(network interface cards) are used for connecting to other computers in a network(computing devices connected together). Extra memory can also be added to the computer using special memory expansion slotsinside the computer. A portable computer that does not have enough space inside to fit expansion cards may use an external device called a port replicatorto provide connections for peripherals.
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Storage devicesin the form of a diskor tape are used to store the programs and data that are not being used. Note that the American spelling of disk is commonly used, although the British spelling, disc, is sometimes used. Before a program or data can be used, it must be transferred from the storage device to the main RAM memory. Hard disksconsist of a set of magnetic coated metal disks that are vacuum-sealed inside a case to keep out the dust. The magnetic surfaces of the disks are formattedusing a read/write headto provide magnetic storage areas. These storage areas form concentric circles called tracksand each track is subdivided into sections called sectors.The disks are rotated at high speed and read from or written to by the read/write head that moves across the surface of the disks. In server computers, hard disks can be connected together and made to operate as one unit using RAID(a redundant array of inexpensive disks). This can speed up the system and provide a way of recovering data if the system crashes(fails suddenly and completely, usually referring to the failure of a hard disk). There is a variety of optical storage devices that use laser light to read or write to a disk, including: CD-ROMs(compact disk read only memory), CD-R(recordable compact disk), CD-RW(re-writable compact disk), DVD(digital versatile disk - previously known as digital video disk).
An input devicecalled a barcode readeris a special type of scannerfor reading barcodes(a set of printed bars of varying thickness that are used to identify a product e.g. used to price items in supermarkets).
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When comparing computers, the powerof the computer is important. This is mainly determined by the speedand capacity(size) of each part of the computer.
Speed is measured in hertz(Hz) i.e. cycles per second.
Capacity is measured in bytes(B) where 1 byte = 8 bits(binary digits) = 1 character.
When specifying a computer the following are normally quoted:
1) the speed of the processor (M Hz - megahertz, GHz - gigahertz)
2) the capacity (size) of the memory (MB -megabytes)
3) the capacity (size) of the magnetic storage devicese.g. hard disk, floppy disk (MB -megabytes, GB - gigabytes)
4) the speed of the optical storage devicese.g. CD-ROM, DVD (given as a multiple of the speed of the first devices produced e.g. 24x = 24 times, 12x = 12 times)
5) the display monitor size (measured in inches diagonally across the screen surface)
6) the monitor image quality (resolution)given by the number of pixels(picture elements) that are used across and down the screen e.g. 800 x 600, or by the graphics standard used e.g. VGA(video graphics array), SVGA(super video graphics array) g the graphics card memory size (MB -megabytes)
7) the speed of the modem (measured in kbps- kilobits per second)
Two different number systems are used in computer specifications:
a) The decimal system,which consists of ten digits from 0 to 9, is used for measuring speed.
b) The binary system,which only has two digits (1 and 0), is used for measuring capacity.
e.g. 1.7 GHz = one point seven thousand million cycles per second 256 MB = 256 x220 bytes = approximately two hundred and fifty six million bytes
Communication is provided between applications programs(word processors, drawing programs, etc.) and the computer hardware(the physical components of a computer system) by a set of programs collectively known as the operating systeme.g. Microsoft Windows, MacOS.
The following prefixes are also used in measurements:
| Decimal system | Binary system | |
| kilo | 103 = 1 thousand | 210= 1,024 |
| mega | 106= 1 million | 220= 1,048,576 |
| giga | 109= 1 thousand million | 230 = 1,073,741,824 |
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