Library and Information Science

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1a. Computer hardware refers to the physical parts or components of a computer such as monitor, keyboard, Computer data storage, hard drive disk, mouse, printers, CPU (graphic cards, sound cards, memory, motherboard and chips), etc. all of which are physical objects that you can actually touch. In contrast, software is untouchable. Software exists as ideas, application, concepts, and symbols, but it has no substance. A combination of hardware and software forms a usable computing system. They are input devices, output devices, storage, and processing.

2. The functions of the following hardware in a computer network I. Modem
Ii. Multiplexers
Iii. Switches
Iv. Routers
V. Bridges
The Function of a Modem
A modem changes computer data into a signal that can travel over a phone or cable line, and a modem at the receiving end turns the information back into a digital form. Cable And DSL Modems
The most common types of modems in households today are cable and DSL modems. A cable modem takes the analog signal sent over a cable television service's lines while a DSL modem does the same thing over the phone line. modems essentially serve the same purpose. Modems And Routers

Some modems today double as wireless routers, but this additional functionality is not an inherent part of all modems. With this capability, the modem can send signals wirelessly to computers on the network it hosts within the range of that modem. If modem does not have this feature, we can easily make use of a wireless router , By setting up a wireless network, a modem can be put in a less noticeable part of an office of at home. A multiplexer (also called a data selector or mux) is a hardware device that accepts multiple inputs and allows only one to go through as an output. Some multiplexers perform both multiplexing and demultiplexing. Demultiplexing is the opposite of multiplexing, and involves the conversion of one input into multiple output channels. A multiplexer allows multiple users or applications to share a common physical medium by allocating bandwidth appropriately. Each user is assigned a particular portion of the bandwidth (or a time share), so that the transmission medium is more efficiently utilized. There are four types of multiplexing methods commonly employed, including space division multiplexing, frequency division multiplexing, time division multiplexing and address multiplexing. Network bridging describes the action taken by network equipment to allow two or more communication networks, or two or more network segments, to create an aggregate network. Bridging is distinct from routing which allows the networks to communicate independently as separate networks. A network bridge is a network device that connects more than one network segment. In the OSI model bridging acts in the first two layers, below the network layer.

There are four types of network-bridging technologies: simple bridging; multiport bridging; learning, or transparent bridging; and source route bridging. Transparent bridging was originally developed by the Digital Equipment Corporation (DEC) in the 1980s.

A router is a device that forwards data packets between computer networks, creating an overlay internetwork. A router is connected to two or more data lines from different networks. When a data packet comes in one of the lines, the router reads the address information in the packet to determine its ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey. Routers perform the "traffic directing" functions on the Internet. A data packet is typically forwarded from one router to another through the networks that constitute the internetwork until it reaches its destination node. The Function of an Internet Router

All of these networks rely on NAPs, backbones and routers to talk to each other. What is incredible about this process is that a message can leave one...
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