www.ciscopress.com copyright 2002cisco press: ccna instructor’s manual year 1 - chapter 1/cisco 1...

www.ciscopress.comCopyright 2002 Cisco Press: CCNA Instructor’s Manual

Year 1 - Chapter 1/Cisco 1 - Module 1

Computer BasicsBy

Robert M. Cannistra


Objectives

• Describe the basic computer hardware components• Understand computer software basics• Understand the binary numbering system• Define networks and networking• Define digital bandwidth


Computer Hardware Components

• Electronic Components– Connector, IC, LED, resistor, transistor

• Personal Computer Subsystems– Bus, CD-ROM drive, CPU, disk drives, microprocessor,

motherboard, RAM, ROM

• Backplane Components– Mouse port, network card, parallel port


All Computers Have a CPU, Memory, Storage, and Interfaces.


Network Interface Cards

• When you select a network card, consider the following three factors:– Type of network– Type of media– Type of system bus

• Installing a NIC in a PC


Computer Software

• Web Browsers– A Web browser acts on behalf of a user by

• Contacting a Web server• Requesting information• Receiving information• Displaying the results on a screen

• Plug-Ins– Flash/Shockwave, QuickTime, Real Audio


Number Systems• Knowing What Base Someone Refers To

– Decimal uses 10 digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.– Binary uses 2 digits: 0 and 1.

• Base Conventions– 101 in Base 2 is spoken as one zero one.

• Working with Exponents– 103 = 10 X 10 X 10 = 1000– 24 = 2 x 2 x 2 x 2 = 16

• Binary Numbers– Use principle of place value just as decimal numbers do


Base 10 (Decimal) Numbers


Base 10 Calculations• The upper table shows the

actual math.• The lower table is a

simplified version that requires the following:

– Start the value row and position row with 1 in the rightmost box.

– Each subsequent value is current value times the base (10 in this case)

– Value to be calculated is entered in the digit row.

– Multiply digit amount times value entry above.


Base 2 Table

27 26 25 24 23 22 21 20

128 64 32 16 8 4 2 1


Base 2 (Binary) Numbers


Base 2 Calculations8-Bit Values

Binary Value: 10101010

Binary Value: 11101001

Start the value row and position row with 1 in the rightmost box.

Each subsequent value is the current value times the base (2 in this case).


Binary Number System

• Even and Odd– A binary number is a multiple of 2 (even number) if

the rightmost digit is a 0.– A binary number is odd if the rightmost digit is 1.


Converting Decimal to Binary

Example: 35 = 32 + 2 + 1 = 00100011

27 26 25 24 23 22 21 20

128 64 32 16 8 4 2 1

0 0 1 0 0 0 1 1


Converting Decimal to Binary

Start by dividing the decimal by the largest number in the Value row that will go.


Looking at the Table Relationships

The table will work with larger numbers, such as this 12-bit example.

Sometimes its easier to subtract the 0 values from 255 (largest 8-bit value).

-

For any number in the value row, the sum of all numbers to the right is the current value minus 1 (64 - 1 = 63).


Powers of 2 for Non-Math Majors

Powers of 2 are used extensively in networking.

One solution:

1. Start with 2 (which is 21).

2. Double the number to get the next value.

3. If you need 26, continue until you have 6 values. Look over the example to the right. The second column is included only for reference.


Binary Number System Exercises

1. Convert the binary number 1010 to Base 10.2. Convert the Base 2 number 11110000 to decimal

notation.3. Convert the decimal number 1111 to binary

notation.4. Convert the decimal number 198 to binary notation.


Network and Networking

• Data Networks• Data Networking

Solutions– Local-area networks– Wide-area networks


LANS Are Designed To:

• Operate within a limited geographic area• Allow many users to access high-bandwidth media• Provide full-time connectivity to local services• Connect physically adjacent devices


LAN Devices


WAN Technologies Include

• Analog modems• Integrated Services Digital Network (ISDN)• Digital Subscriber Line (DSL)• Frame Relay• Asynchronous Transfer Mode (ATM)• T (US) and E (Europe) Carrier Series: T1, E1, T3, E3• Synchronous Optical Network (SONET)


WAN Devices


Bandwidth Measurements


Digital Bandwidth• Two Analogies That Describe Digital Bandwidth

– Width of a pipe

– Number of lanes on a highway

• Media Bandwidth Differences– Category 5 UTP – 100 meters maximum physical distance

– Multimode (62.5/125um) optical fiber – 2000 meters

– Modem – 56 Kbps = 0.056 Mbps

– T1 – 1.544 Mbps


Bandwidth Pipe Analogy


Bandwidth Highway Analogy


Digital Bandwidth (cont.)

• Data Throughput in Relation to Digital Bandwidth– Factors that determine: internetworking devices, type of date

being transferred, topology, number of users, user’s computer

• Data Transfer Calculation– Estimated time = size of file / bandwidth

• Why Is Bandwidth Important?– Bandwidth is finite!


Media Bandwidth


Importance of Bandwidth

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