Listen to the text and try to understand it.

Exercise 3

Give the name to the text.

Exercise 4

Read and translate the text using the words before.

1. Digital Technologies

1.1 What are DT used for and where

 

Digital Technologies [ or DT as abbreviation] – the kind of technologies based on digital signals and digital data storage principles and rules.

People use DT because it’s more simple to use and store data in digital format. For example, usual phrase “Hello, friend!” can be recorded by computer [DT] and by tape recorder. So, this phrase will take about 20 KB of memory [it’s very small size – usual Floppy Disks can keep 1,44 MB of data], it’s very easy to use that small file. But in tape recorder, it will take some place on the tape and it’s very uncomfortable to look for that area of tape. In computer, you’ll find that file in seconds!

So, one of the most known advantages of DT is that they are easy to use and store. These advantages are the reasons of using DT in a lot of devices.

The devices based on DT are everywhere – from your washing machine with small processor to make washing process simpler to complicated supercomputers in NASA researching laboratories. Any device with some ‘intelligence is based on DT.

 

Main principles of Digital Technologies

Digital signals

The data in devices is transformed into signals. The DT are based on digital signal [look at the scheme1].The form of this signal is very simple – that’s another reason of using DT.

The signal of digital device can be in 2 conditions – it can be 1 or 0. 1 and 0 conditions of signal, but it cannot be 1A or 0A or other conditions. It means that signals in the conductor can be or not be. They can be in another system of differences between signal conditions. This system is divided into different devices.

 

Data, its units and storage

 

The data in DT is very easy to write, copy and read. I will tell you about the system of counting data.

The data of DT is based on binary counting system. The simplest data unit is bit [from BInary digit]. To make understanding easier, we can say that bit is a digital signal, which can be 1 or 0. So, bit can be 1 or 0 too. Other most known data unit is byte. The byte is a complex unit – it consists of 8 bits.

Then, as in Physics, there are some all known prefixes – ‘kilo-’, ‘mega-’, ‘giga-’. In Physics these prefixes mean accordingly ‘thousands of…’, ‘millions of…’, ‘billions of…’. But!!! In DT these prefixes mean other values, because the counting system isn’t decimal, the values of KByte, MByte and GByte are not so simple. They are 1024, 1048576 and 1073741824 bytes respectively.

The storage of data is different in different devices.

The data in computers can be stored in several ways. It means there are many data storage devices. These data storage devices can be divided into some groups:

1. Multiple usable devices [those devices where you can read and write the information as frequent as you want]: hard and floppy disks, CD-RW disks, LS-120 disks, magnetic tapes, and ZIP disks.

2. Multiple readable devices [those devices where you can write the information only once, but any time read it you can]: CD-ROM disks, MiniDisks, Flash ROM memory devices.

3. Other devices: CMOS, RAM, Cache and Buffer devices.

The data in computer is stored in a kind of blocks – clusters. The cluster is an array of bits. Modern computers have 4 Kbytes in cluster as default value. The computer stores the list of clusters in a special File Allocation Table [aka FAT]. The FAT says to a computer where it can “find” the needed data. Some modern computer viruses destroy this FAT, and the computer became disorganized, and it doesn’t work because it doesn’t “know” where the files can be found.

Connection with AT

 

There is no mistake in the name of this device. The first reason to write it like this is that the name of it was made of two words – modulation and demodulation. The second reason is that people, who know computer and programming very well, often write computer [and not only] words like this if they’re made of more than one word [for example, ‘OutTextXY’].

 

Digital signal to analog

 

First principle of the work of modem has the name ‘modulation’. It sounds like this because all analog signals have their modulation – the sum of waves with low and high frequencies. The word ‘modulation’ also means ‘converting digital signal to analog’.

So, the first principle how to use is modulation. In the simplest point of view, modem takes the carrier tone [a kind of main sound – modem uses carrier tone to generate low or high frequency sounds] and modulates it – makes sounds from the bits. Look at the schemes 1 and 2 to see how the digital signal can be transformed to analog.

 

Analog signal to digital

 

Second principle of modem’s work has name ‘demodulation’. As you decide, this is an opposite of the first. The word ‘demodulation’ means ‘converting analog signal to digital’.

In the simplest point of view, modem takes the sound, compares it with the carrier tone to separate high and low sounds and demodulates it – makes sounds from the bits using carrier tone as an etalon.

Look at the schemes 2 and 1 to see an example of transforming the analog signal to digital.

 

Using of modulation and demodulation

As you have head, the processes of modulation and demodulation are used in modems. Modems are the main representatives of the devices that use modulation and demodulation. Only one modem can do many things.

It can be used in Dial-Up Networking to have the possibility of exploring the WorldWideWeb – Internet.

Another use of modems is to connect two computers with the ability to e-talk in real-time mode and to send and get files. It is very good because in our country nobody wants to spend his own money using the Internet and if somebody has a file, he can send it to anybody without spending money.

And the last example is IP-Telephony. It’s a phoning using the Internet. It is used if you need to call to another city or country without paying much money. You just pay for the Internet access and talk via some special servers.

 

Exercise 5

Answer the following questions:

1. What are Digital Technologies?

2. Why do we use DT?

3. What do you know about Digital signal?

4. What is the data in DT based on?

5. Is bit a digital signal or a digital information?

6. How many bits are there in a unit?

7. How can data be stored in computers?

8. What are clusters?

9. What are the principles of modem’s work?

10. Another use of modems is connected between two computers with the ability to e-talk, isn’t it?

 

Exercise 6

Make up a plan of the text.

Exercise 7

Complete the sentences using the text:

1. People use DT because …

2. The data of DT is based …

3. But in tape recorders it will take some place on the tape and …

4. These data storage devices can be divided …

5. The second reason is that people, who know the computer and programming …

6. The computer stores the list of clusters in …

7. Modems are the main representatives of …

8. It is a phoning using …

9. The word “demodulation” means …

10. Some modem computer viruses destroy this FAT and …

Exercise 8

State True or False sentences:

1. So, one of the most known advantages of DT is that they are difficult to use and store.

2. To make understanding easier, we can say that bit is a verbal signal, which can be A or W.

3. The computer stores the list of clusters in a special File Allocation Table [aka FAT].

4. The second reason is that people, who know computer words do not like this if they’re made of more than one word.

5. In the simplest point of view, modem takes the sound, compares it with the carrier tone to separate high and low sounds and demodulates it – makes sounds from the bits using carrier tone as atalon.

6. You just pay for the Internet access and talk via some special servers.

7. But in tape recorder, it will take some place on the tape and it’s very comfortable to look for that area of tape.

8. Any device with some “intelligence” is not based on DT.

9. Other most known data unit is byte.

10. The data in computers can be stored in several ways.

 

 

Exercise 9