Central database. The PC passes the query, written in a special

Language (e.g. Structured Query Language - SQL), to the mainframe, which then parses the query, returning to the user only the data requested. The user

55 might then use his PC to draw graphs based on the data. By passing back to the user's PC only the specific information requested, network traffic is

Reduced. If the whole file were transmitted, the PC would then have to perform the query itself, reducing the efficiency of both network and PC.

In the 1980s, at least 100,000 LANs were set up in laboratories and offices around the world. During the early part of this decade, synchronous orbit

Satellites lowered the price of long-distance telephone calls, enabling computer data and television signals to be distributed more cheaply around

The world. Since then, fibre-optic cable has been installed on a large scale, enabling vast amounts of data to be transmitted at a very high speed using light

Signals.

The impact of fibre optics will be considerably to reduce the price of network access. Global communication and computer

Networks will become more and more a part of professional and personal lives as the price of microcomputers and network access drops. At the same time,

Distributed computer networks should improve our work environments and technical abilities.

L

Task 4

Read this summary of the text and fill in the gaps using the list of words below.

Computer networks link computers locally or by external communication lines
___________, allowing data to be exchanged rapidly and

between local area and wide area networks is,

however, becoming unclear. Networks are being used to perform increasingly diverse tasks, such as carrying e-mail providing access to public databases,

and for.

.. Networks also allow users in one locality to share

resources.

Distributed systems use networked computers. PCs or 1_

provide the user.

.. Mainframes process __

and return the results to the users. A user at his PC might make a query against a central database. The PC passes the query, written in a special

language, to the mainframe, which then '______________ the query,

returning to the user only the data requested. This allows both the network and the individual PC to operate efficiently.

In the 1980s, at least 100,000 -______________ were set up world-wide. As

orbit satellites have lowered the price of long-distance

telephone calls, data can be transmitted more cheaply. In addition,

cable has been installed on a large scale, enabling vast

amounts of data to be transmitted at a very high speed using light signals. This| will considerably reduce the price of network access, making global networks more and more a part of our professional and personal lives. Networks should

Ii

also improve our work!!_____________ and technical abilities.

distinction fibre-optic protocols synchronous

distributed systems LANs queries

environments parses screen lumdlint)

TaskS

Task 6

Using the line references given, look back in the text and find words that have] similar meaning to:

1 unclear (lines 15~2O)

2 place (lines 25-30)

3 carry out (lines 3 5-40)

4 cost (lines 70-75)

5 world-wide (lines 80-8 5)

Now look back in the text and find words that have an opposite meaning to:

1 disparate (lines 10-15)

2 conflict v (lines 30-3 5)

3 preventing (lines 70-75)

4 tiny (lines 75-80)

5 increase (lines 80-8 5)

Writing

Translate the third paragraph, beginning 'Distributed computer systems...' into your own language.

Listening

]

Listen to this extract from the radio programme Computerworks about LANs. Indicate whether the following items are mentioned (J) or not mentioned (x).

1 LJ LANs are equally useful to large and small companies.

2 LJ Companies can install their own LANs, provided they are not too big.

3 I_ I Whether or not a company builds a 'do-it-yourself LAN depends on the

amount of space available for the installation.

4 LJ It is sometimes still possible to install part of a LAN if you don't have the

computer knowledge or time to do the whole job yourself.

5 LJ You need at least three years' computer maintenance experience before

you should attempt to install a LAN.

6 LJ In order to install your own LAN, you need to be used to opening up

computers, adding and removing expansion boards, and consulting computer documentation.

7 LJ When installing your own LAN you should expect to have to repeat the

same process several times.

8 LJ The installation process often causes computers to break down.

r

Task 9 CSJ Read this extract from the tapescript and try to fill in each gap with an

appropriate word.

Task 10

When you're installing a LAN, you may be_____

as much as a day or so. A lot depends on how

proceeds, and that depends on your own______

can have each of your machines!____________

of:

minutes at a time. If you can't live without your computers for a while, you

doing it yourself.

. This may

require you to install junction boxes in walls, do the wiring, and maybe install

electrical'

and if you aren't a__________

this part, at least. Of course, if you're installing your LAN in one room, then
you might not need to hire_____________

Now listen again to the last part of the recording. Check to see whether your answers match those used by the speaker.

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