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Computing Basics

Honolulu Community College

Cisco Academy Training Center

Semester 1

Version 2.1.1

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Overview Components of the computer. Role of the computer in networking.

Internet is like a tree, and computers are like leaves on the tree.

Computers are sources and receivers of information on the Internet.

Computers are an integral part of a network, and they play a vital role in the world of work. Many business applications like spreadsheets,

word processors, browsers, etc.

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Major Components of a PC Small, discrete components:

Transistor Integrated circuit (IC) Resistor Capacitor LED (light emitting diode)

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Major Components of a PC (cont.) Personal computer subsystems:

CPU (central processing unit) Memory:

RAM, ROM CD-ROM drive Floppy disk drive

Bus System unit Expansion slots Power supply

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Major Components of a PC (cont.) Backplane components:

Backplane network card (NIC) or LAN adapter Video card Sound card Parallel ports Serial ports Mouse port

For a laptop, cards and slots are referred to as PCMCIA.

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Information Flow in a Computer Some important information flow:

Boot instructions (ROM). Software applications (moved into RAM). Application information (data) -stored in RAM. Saved information - from RAM to storage device. Exported information - from RAM and CPU to

external devices. Almost all data flows in parallel through the bus.

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NIC Provides network

communications capabilities. Also called a LAN adapter. Communicates serially with

network, in parallel with computer. Requires an IRQ, I/O address, and upper

memory addresses (for DOS or Windows). 3 factors in selecting NIC.

Type of network (Ethernet, Token Ring, or FDDI). Type of media. Type of system bus.

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Installing a NIC You may need to install a NIC because:

there is none. NIC is bad or damaged. Need to upgrade from 10Mbps (standard

Ethernet) to 100Mbps (Fast Ethernet). Need to alter settings on a NIC using a

jumper.

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Configuring Network Settings on PC Computer software - essentially to get the

computer to do what you want. Procedure:

1.select the NIC for software configuration. 2.input the correct TCP/IP address. 3.adjust the display (if necessary). 4.install and set up the browser. 5.perform a few other tasks (if necessary).

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Web Browser Software application that interprets html

(hypertext markup language). Two most popular browsers:

Netscape Communicator. Internet Explorer.

Terms: Hyperlinks - commands that point to another

location in PC or on network. Plug-ins - special purpose software used to

display special or proprietary files in browser.

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Binary Number System Computers use binary signals either "on" or "off",

corresponding to 1 or 0. This is a base 2 or binary number system.

Bits - individual 1 or 0. Byte - group of 8 bits.

In decimal, multipliers for each digit is a power of 10. 368 = 3x102 + 6x101 + 8x100

In binary, multipliers for each bit is a power of 2. 1101 = 1x23 + 1x22 + 0x21 + 1x20 = 13(decimal).

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Binary to Decimal Conversion Converting binary to decimal is understanding

what a abase 2 number system is. Each bit has a multiplier (power of 2).

Powers of 2 are: 1, 2, 4, 8, 16, 32, 64, 128, etc. 10011101(binary) =

1x27 + 0x26 + 0x25 + 1x24 + 1x23 + 1x22 + 0x21 + 1x20 = 128 + 0 + 0 + 16 + 8 + 4 + 0 + 1 = 157 in decimal.

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Decimal to Binary Conversion Note that any decimal number is made up of a

unique sum of powers of 2. Ex1: 25 decimal = 16 + 8 + 1

In binary: 11001 (i.e. 1x16 + 1x8 + 0x4 + 0x2 + 1x1) Ex2: 107 decimal = 64 + 32 + 8 + 2 + 1

In binary: 1101011

Note: Curriculum gives a general method to convert any decimal to binary.

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Other Binary Calculations How many different values can you represent with

a 5 bit number? In general: 2n values with n bits. 25 = 32 different values (from 0 to 31 in decimal).

What is the largest value you can represent with an 8 bit number? In general, highest value is 2n-1, with n bits. 28 - 1 = 255 Note you can represent 256 values with 8 bits (from

0 to 255 in decimal).

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What is Networking? Networking is the interconnection of

workstations, peripherals terminals and other devices.

Networking addressed 3 problems: How to avoid duplication of equipment and

resources. How to communicate efficiently. How to set up and manage a network.

First networks were LANs (local area networks), in a limited geographical area.

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Networking Protocols Networking protocols are a formal set of rules

and conventions, determining how devices communicate on the network.

Protocols are like languages. Devices must use the same protocol in order to

communicate.

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Evolution of Networking Early 1980s - rapid development of networking. Manufacturers developed their own equipment,

leading to problem of compatibility between equipment of different vendors.

Initial networks were LANs, generally using one manufacturer’s equipment.

As business demands on networking grew, networks grew to span large geographical areas, and became WANs (wide area networks). WANS can connect cities or even countries.

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WAN Technologies Some common WAN technologies are:

modems ISDN (Integrated Services Digital Network) DSL (Digital Subscriber Line) Frame relay ATM (Asynchronous Transfer Mode) The T (US) and E (Europe) Carrier Series:

T1, E1, T3, E3, etc. SONET (Synchronous Optical Network)

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Digital Bandwidth Bandwidth - a measure of how much information

can flow from one place to another in a given amount of time.

Bandwidth represents the capacity of network connection (max possible data rate).

Bandwidth is measured in bits per second.

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Bandwidth is limited by the media

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Bandwidth is limited by the service

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Bandwidth is limited by the service

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Throughput The actual data rate you get. Often far less then the maximum possible digital

bandwidth of the medium.

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Bandwidth vs Throughput When you design a network, you consider the

theoretical bandwidth. Your network will be no faster than what your media will allow.

When you actually work on networks, you measure throughput and decide if the throughput is adequate for the user.

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File Transfer Time Calculations

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Calculations A 10 Mbps channel is used to transfer a 5Mbyte

file. What is the fastest time required to transfer the file? T=S/BW = 5MB(8bits/byte)/10Mbps = 4 secs.

Due to congestion, the throughput of the channel is only 40% of capacity. What is the actual time to transfer the file? P = throughput = 40%(10Mbps) = 4Mbps. T= S/P = 5MB(8bits/byte)/4Mbps = 10 sec.

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Importance of Bandwidth It is finite. It can save money. It’s a key measure of network design and

performance. It’s a key to understanding the Internet. Demand for it increases constantly.

The End