Transcript Computer Basics

Year 1 - Chapter 1/Cisco 1 - Module 1
Computer Basics
By
Robert M. Cannistra
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
Objectives
•
•
•
•
•
Describe the basic computer hardware components
Understand computer software basics
Understand the binary numbering system
Define networks and networking
Define digital bandwidth
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
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
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
All Computers Have a CPU,
Memory, Storage, and Interfaces.
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
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
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
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
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
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
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
Base 10 (Decimal) Numbers
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
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.
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
Base 2 Table
27
26
25
24
23
22
21
20
128
64
32
16
8
4
2
1
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
Base 2 (Binary) Numbers
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
Base 2 Calculations
8-Bit Values
Binary Value: 10101010
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 Value: 11101001
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
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.
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
Converting Decimal to Binary
Example: 35 = 32 + 2 + 1 = 00100011
27
128
26
64
25
32
24
16
23
8
22
4
21
2
20
1
0
0
1
0
0
0
1
1
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
Converting Decimal to Binary
Start by dividing the decimal by the largest number
in the Value row that will go.
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
Looking at the Table
Relationships
The table will work with larger numbers, such
as this 12-bit example.
For any number in the value
row, the sum of all numbers to
the right is the current value
minus 1 (64 - 1 = 63).
Sometimes its easier to subtract the 0 values
from 255 (largest 8-bit value).
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
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.
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
Binary Number System Exercises
1.
2.
3.
4.
Convert the binary number 1010 to Base 10.
Convert the Base 2 number 11110000 to decimal
notation.
Convert the decimal number 1111 to binary
notation.
Convert the decimal number 198 to binary notation.
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
Network and Networking
• Data Networks
• Data Networking
Solutions
– Local-area networks
– Wide-area networks
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
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
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
LAN Devices
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
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)
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
WAN Devices
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
Bandwidth Measurements
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
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
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
Bandwidth Pipe Analogy
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
Bandwidth Highway Analogy
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
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!
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
Media Bandwidth
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com
Importance of Bandwidth
Copyright 2002
Cisco Press: CCNA Instructor’s Manual
www.ciscopress.com