Task  4. Find the answers to these questions in the following text.

1. What purpose does the Internet address have apart from identifying a node?

2. What data-delivery systems are mentioned in the text?

3. What do IP modules need to know about each other to communicate?

4. How many Internet addresses does a gateway have?

5. What does UDP software do?

6. When does the TCP part of TCP/IP come into operation?

7. What processes are performed by TCP software to provide reliable stream service?

8. What standard protocols are mentioned which are used to deal with the data after TCP brings it into the computer?

How TCP/IP Links Dissimilar Machines

At the heart of the Internet Protocol (IP) portion of TCP/IP is a concept called the Internet    address. This 32-bit coding system assigns a number to every node on the network.

 There are various types of addresses designed for networks of different sizes, but you can write every address with a series of numbers that identify the major network and the sub-networks to which a node is attached. Besides identifying a node, the address  provides a path that gateways can use to route  information from one machine to another.       

Although data-delivery systems like Ethernet or X.25 bring their packets to any machine electrically attached to the cable, the IP modules must know each other’s Internet addresses if they are to communicate. A machine acting as a gateway connecting different TCP/IP networks will have a different Internet address on each network. Internal look-up tables and software based on another standard - called Resolution Protocol - are used to route the data through a gateway between networks.

Another piece of software works with the IP-layer programs to move information to the right application on the receiving system. This software follows a standard called the User Datagram Protocol (UDP). You can think of the UDP software as creating a data address in the TCP/IP message that states exactly what application the и data block is supposed to contact at the address the IP software has described. The UDP software provides the final routing for the data within the receiving system.

The Transmission Control Protocol (TCP) part of TCP/IP comes into operation once the packet is delivered to the correct Internet address and application port. Software packages that follow the TCP standard run on each machine, establish a connection to each other, and manage the communication exchanges. A data-delivery system like Ethernet doesn’t promise to deliver a packet successfully. Neither IP nor UDP knows anything about recovering packets that aren’t successfully delivered, but TCP structures and buffers the data flow, looks for responses and takes action to replace missing data blocks. This concept of data management is called reliable stream service.

After TCP brings the data packet into a so computer, other high-level programs handle it. Some are enshrined in official US government standards, like the File Transfer Protocol (FTP) and the Simple Mail Transfer Protocol (SMTP). If you use these standard protocols on different kinds of computers, you will at least have ways of easily transferring files and other kinds of data.

Conceptually, software that supports the TCP protocol stands alone. It can work with data received through a serial port, over a packet- on switched network, or from a network system like Ethernet. TCP software doesn’t need to use IP or UDP, it doesn’t even have to know they exist. But in practice TCP is an integral part of the TCP/IP picture, and it is most frequently used with those two protocols.

Task  5. Mark the following statements as True or False:

1. Internet addresses are an integral part of the IP protocol.

2. Internet addresses can be written as a series of numbers.

3. UDP software provides the final routing for data within the receiving system.

4. UDP recovers packets that aren’t successfully delivered.

5. TCP only works with packet-switched networks.

6. TCP only works when it is combined with IP.

LESSON 22

Miniature Radios and computers

Pocket Radios

Task  1. Read and translate the text:

Задание 1. Прочитайте и переведите текст

The transistor's compactness and low power requirements also brought a new day in a host of simpler devices. Radio receivers hardly larger than a package of cigarettes were on a reality. In 1956-58 the transistor found one of the most spectacular applications. It helped Russian and American specialists to launch the first satellites and to open the space age. Only a few of the biggest satellites have been able to carry vacuum-tube equipment. Most satellites have appended on transistors not only for reporting back to the earth but for operating the instruments with which the satellites explored the mysterious regions around the earth. But the most striking aspect of the transistor is not the host of devices it made possible. More important was its effect on a new branch of science and technology which may be called “solids-state electronics”.

Pocket-size TV Camera

The ultra-miniature TV camera was made possible by a new design approach, which combines transistors, specially developed transistor circuitry and a new half-inch Videocon camera tube.

The pocket-size TV camera (JTV-1) weighs less than, pound and measures only 1 7/8 the by 2 3/8 the by 4 1/2 inches. It can be operated in the palm of the hand, used with an attachable pistol-grip handle, bolted to wall or floor, or mounted on a tripod. It is the first TV camera of its type to incorporate a photoelectric control, which enables the camera to accommodate changes in the order of 100 to 1 in scene lighting. Made rugged for military airborne, mobile, and field requirements the pocket-size camera has high resistance to shock and vibration. Simple in design and operation, the camera can be operated by non-technical personnel.

Molecular Computer

A small computer with molecular blocks as its "brain" is being developed. The new device, called a Mol-E-Com, will weigh 14 pounds and occupy less than one-third of a cubic foot. A solid semiconductor crystal with its internal structure rearranged as a functional electronic block replaces the tubes, transistors, and resistors in conventional miniaturized circuitry.

Mol-E-Com is expected to have the same capabilities as a transistorized computer ten times its size and weight, making it useful for rockets