1. Communications Letts Study Guide GCSE Information Systems and IT Chapter 15

2. FAX Fax is a widely used method of transmitting the contents of documents using ordinary telephone lines. Fax transmission does not usually involve the use of computers.

3. VIDEOTEXT Videotext systems use a computer to transmit data to user's screens. The main systems are:

4. TELETEXT sends out information using ordinary television signals can only be viewed on specially adapted televisions; it is not interactive. The user cannot send messages back to the computer.

5. VIEWDATA viewdata, which uses the telephone to link users back to a host computer. -requires a modem and a terminal or a microcomputer; -is interactive the user can send messages back to the computer.

6. NETWORKS A computer network is a system of computers and workstations connected together. A local area network (LAN) is a network in a small area, often one building, usually connected by cables. A wide area network (WAN) is a network operating over long distances using telephone or similar links.