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www.ciscopress.comCopyright 2002 Cisco Press: CCNA Instructor’s Manual
Year 1 - Chapter 1/Cisco 1 - Module 1
Computer BasicsBy
Robert M. Cannistra
www.ciscopress.comCopyright 2002 Cisco Press: CCNA Instructor’s Manual
Objectives
• Describe the basic computer hardware components• Understand computer software basics• Understand the binary numbering system• Define networks and networking• Define digital bandwidth
www.ciscopress.comCopyright 2002 Cisco Press: CCNA Instructor’s Manual
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
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All Computers Have a CPU, Memory, Storage, and Interfaces.
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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
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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
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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
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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.
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Base 2 Table
27 26 25 24 23 22 21 20
128 64 32 16 8 4 2 1
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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).
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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.
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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
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Converting Decimal to Binary
Start by dividing the decimal by the largest number in the Value row that will go.
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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).
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For any number in the value row, the sum of all numbers to the right is the current value minus 1 (64 - 1 = 63).
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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.
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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.
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Network and Networking
• Data Networks• Data Networking
Solutions– Local-area networks– Wide-area networks
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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
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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)
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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
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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!