Ways to minimize disadvantages of a network.

1. Employ well trained computing staff.

2. Use standard systems.

3. Try to negotiate bulk discounts.

4. Use thin clients instead of full computers.

5. Install an anti-virus program on the server.

6. Schedule frequent virus checks on the server.

7. Buy a good quality server.

8. Buy as powerful a server as you can afford.

9. Purchase a server with hot-swappable components.

10. Install a RAID system on the server.

11. Have a good training scheme for computing personnel.

Linking some of the advantages and disadvantages of a network.

1. Although networks allow data to be shared, they permit viruses to spread quickly.

2. Users can share software on the server; however server failure means that no one can work.

3. Networks are more vulnerable to viruses; however it is easier to check for viruses.

4. Although maintenance is easier, networks require more expertise to maintain.

5. Networks are more complex to set up; however maintenance is easier.

6. Although access to the system can be controlled, networks are more vulnerable to viruses.

7. Hardware and software can be shared; however the whole network depends on the central server.

Technical Reading 1: ‘Asynchronous transmission’.

This method, used with most microcomputers, is also called start-stop transmission. In asynchronous transmission, data is sent one byte (or character) at a time. Each string of bits making up the byte is bracketed, or marked off, with special control bits. That is, a ‘start’ bit represents the beginning of a character, and a ‘stop’ bit represents the end. As a means of checking that the whole character has been transmitted, an error check bit is generated immediately after each character.

Transmitting only one byte at a time makes this a relatively slow method. As a result, asynchronous transmission is not used when great amounts of data must be sent rapidly. Its advantage is that the data can be transmitted whenever it is convenient for the sender.

Diagram 3: ‘Asynchronous transmission’.

a start bit

b error check bit

c stop bit

d start bit

e error check bit

f stop bit

Technical Reading 2: ‘Synchronous transmission’.

Synchronous transmission sends data in blocks of characters. Start and stop bit patterns, called synch bytes, are transmitted at the beginning and end of the blocks. These start and end bit patterns synchronize internal clocks in the sending and receiving devices so that they are in time with each other. Error check bytes are included immediately after each block of characters to ensure that the whole sequence of characters has been correctly transmitted.

This method is rarely used with microcomputers because it is more complicated and expensive than asynchronous transmission. It also requires careful timing between sending and receiving equipment. It is appropriate for computer systems that need to transmit great quantities of data quickly.

Diagram 4: ‘Synchronous transmission’.

a start synch bytes

b character

c character

d error check bytes

e stop synch bytes