4. Translate these sentences into your native language:

1. How does the receiving device know where one character ends and another starts? 2. Users of both sending and the receiving computers must agree on the parity scheme. 3. For example, if computer A is transmitting to computer B, the users of both computers must first agree on a parity scheme (perhaps by having a telephone conversation), then load the communications software, and choose the agreed-on parity scheme by choosing the appropriate software option. It doesn’t matter which scheme is chosen as long as both computers are using the same one- odd or even. 4. As a result, a number of vendors have produced add-on boards.

5. Retell the text.

Text 12

Simplex, Half-Duplex, and Full-Duplex Traffic

Words and word combinations:

Manner of data transmission – способ передачи данных

the direction of data traffic flow – направление потока движения данных

supported by communications links – поддержанная передающей релейной линией

simplex mode – простой способ

environmental devices – прибор контроля окружающей среды

information about temperature, humidity – информация о температуре и влажности

а half-duplex – наполовину двухсторонний

support two-way traffic – поддерживать двухстороннее движение

a walkie-talkie – переносная рация

the transmit button – передающая кнопка

a central computer system – сервер

in both directions simultaneously – в обоих направлениях одновременно

side-by-side tracks – направляющее устройство бок о бок

high-speed communication – высокоскоростная связь

full-duplex – полностью двухсторонний

Besides signals type (analog or digital) and manner of data transmission (synchronous or asynchronous), data communications technology must also consider the direction of data traffic flow supported by communications links such as modems. In the simplex mode, data can travel in only one direction at all times. For example, in some museum settings, environmental devices send information about temperature, humidity, and other conditions to a computer that monitors and adjusts office environmental settings automatically. However, the computer does not send information back to the devices. This simplex mode is also used occasionally in some local area networks.

Receiving Station

Simplex (one direction)

A half-duplex communications link can support two-way traffic, but data can travel in only one direction at one time. This mode of transmission is similar to using a walkie-talkie. When you press the transmit button you can talk, but you cannot receive. After you release the transmit button, you can receive, but you cannot transmit.

Sending and

receiving station

Half-duplex

(in both directions-but not at the same time)

Transmission of data in this mode over long distances can greatly increase the time it takes to communicate data. This delay is due to three factors: (1) the mode, (2) the time required for a device A to transmit a message to device B requesting confirmation that all is ready for transmission, and (3) the time required for device A to receive the confirmation that device B is ready to receive. The half-duplex transmission mode is most commonly used between a central computer system and the terminals connected to it.

Sending and

receiving station

Full-duplex

(in both directions simultaneously)

Full-duplex transmission sends data in both directions simultaneously, similar to two trains passing each other in different directions on side-by-side tracks. This transmission mode eliminates the problem of transmission delay, but it is more expensive than the other two modes. However, when high-speed communication between computers and peripherals is necessary, the expense may be worthwhile.