-Networks -Interfacing -Protocols

-Networks -Interfacing -Protocols

1. Interface

   • interface is the hardware and software needed for the processor to be able to communicate with the device
     • Sometimes the interface hardware comes on an interface board, which has to be fitted into a computer
     • Sometimes the device can just be connected to a socket
       • This is the port through which signals to and from the device travel

2. Networks

   • Advantages
     • Allows sharing of resources
       • Examples
         • Disk Storage
         • Printers
         • Image Scanners
         • Modems and Central Servers
     • Allows sharing of information held on disk drives accessible by all users
     • It is easier to back up data held on a file server than on many individual machines
     • It is easier to store application programs on one computer and make them available to all users
     • Electronic mail can be sent to other users
     • It is easier to set up new users and equipment
     • It allows the connections of different types of computer to communicate
   • Disadvantages
     • If the network file server develops a fault then many users will be unable to run application programs
     • If the network stops operating then it makes accessing various hardware and software resources not possible
     • The quality of the system is based on the system manager's skill
     • It is difficult to make the system secure from hackers
     • Increased traffic can degrade performance

3. Protocols

   • Rules
     • A response is always required
     • One message is sent at a time
     • Specific messages give specific responses
   • Protocols have rules for...
     • detecting a connection
     • handshaking
       • When two devices need to communicate, one device sends a message to the other ('Are you ready to receive data?'). When the other is ready, it sends a signal back to the first device ('Yes, I am ready to receive data')..., and then communication can begin.
     • how to start and end a message
     • how to format a message
     • what to do about errors
     • how to detect a loss of connection and what to do next
     • terminating a connection
   • TCP/IP is the basic communication protocol of the Internet and other networks.
   • HTTP (HyperText Transfer Protocol) is used for transferring web pages between a client and a server on the Internet. It is also used on intranets.
   • FTP (File Transfer Protocol) is used for transferring files from one computer to another. Eg. Uploading web page files to a web server.
   • SMTP (Simple Mail Transfer Protocol) is used for sending an email over the Internet.
   • VoIP (Voice over Internet Protocol) is used for sending voiced messages over the Internet.
   • Wireless protocols enable the transmission of data over a wireless network.