Introduction to Computer Systems and Networks INTRODUCTION In this era of information society, distance and time factor is no longer a barrier to information. Thus the computer network becomes very important to assist in obtaining and providing information or data in a short time. Computer network allows users to obtain information with personal computers through local area network (LAN) up to the international network (Internet). Definition of Network Computer network contribution means two or more computers that are physically separated but connected in its operations. Network is a system of shared equipment (printers and CD-Rom), software, information sharing and communication. Information may be transferred in the network by cable, radio waves, infrared transmitting or satellite. BENEFITS OF USING NETWORK (NETWORKING) File Sharing. Users can share files stored on server or the central computer. Transferring Files. Facilitate the transfer of stored files from one computer to another. Sharing Software (Applications) and reduce the cost. Program allows the user to share applications such as Word, Lotus, Access, etc..In this way it can reduce costs and simplify installation of software. Share data and save you time to enter data. Data can be entered by two or more users into a single application. At the same time, other users can use the data. Share printers, scanners, CD-ROM, etc. Printer or CD-Rom available on a computer can be used by all other users who use computer. Using Electronic Mail (E-Mail) Users can send memos from one computer to another. Local network (Local Area Network) Large network (MAN and WAN) is more useful in terms of geographical area, but many organizations need to connect a local network devices used in a limited. So the following aspects should be considered: Type LAN - User and server (Client-server). Consumers age (Peer to Peer). LAN components. LAN topology. The effect of LAN. The types of LAN There are two types of Local Area Network (LAN) that is: 1. User and the server (client-server) LAN type consists of a server (Server) to treat the other computer that acts as a user (client). Server will be run management center (Centralized) to serve the users in terms of sharing of software applications, data, printers, etc. Usually high-powered Server types: File server (file server) - Save the software and data. Data server (database server) - Save the data. Print server (Print server) - Control one or more printers. Fax server (Fax server) - Managing the delivery and fax. Mail server (Mail server) - Manage your e-mail. Usually this server does not process or alter the data transmitted. The server does not need to know what types of files, but it was busy answering a request from a user's computer for files that saved in. Examples of Operating System software Network / Network Operating System (NOS) is Novell Netware, Windows NT, UNIX Components for LAN 1. Computer server (Server) Usually consist of a Pentium Celeron 333A of the system. 64MB SDRAM, 4GB hard disk, 15 "digital color monitor, 40x CD-ROM drives, Network Interface Card (Ethernet Network Card), 8MB SVGA card and sound card 16-bit 3D 2. Stassen work (Workstation) Usually consist of a system of over 486, 16MB RAM, 540MB hard disk, 15 "digital color monitor, 40x CD-ROM drives, Network Interface Card (Ethernet Network Card), 8MB SVGA card and sound card 16-bit 3D. 3. Network Interface Card / Network Interface Card (NIC) NIC must be installed on each computer and connected to a network with a cable or infrared rays. Here is some of NIC. Ethernet Card-Example: 3Com (RM 350), D-Link (RM 220), 10Base (RM 120) Token Ring Card Local Talk Connector 4. Cable There are four common types of cables. Here is a comparison between the cables in terms of compatibility and capability.