NT1210
Introduction to Networking
• Name: Williams Obinkyereh
MSc. IT, Post Masters Software
Engineering
DSC (Doctor of Computer Science)
Student.
• Contacts:
• Phone: 612-516-9712
• Email: obinkytt@yahoo.co.uk
Introduction
• Class introduction
• Introduction of Course Syllabus.
– Course Summary
– Lab Infrastructure (Mock)
– Course Plan
– Evaluation
– Academic integrity
• Discussion and questions about syllabus.
• Send me email: Name, phone number and
a reliable email address.
NT1210 Introduction to Networking
Unit 1:
Chapter 1, Introduction to
Computer Data
4
Objectives
 Identify the major needs and stakeholders for computer
networks and network applications.
 Describe how digital devices store data.
 Describe the differences between input and output
devices.
5
Various Types of Computer/Computing Devices
Images of Various Types of Computers/Computing Devices
6
Figure 1-1
Introducing Data and Information, Bits and Bytes
 Computers use binary digits (bits) to record information
electronically
 Bits represent either value of 0 or 1
 Bit is smallest unit of data computers work with
 Computers work with multi-digit binary numbers
 Nibble
 Byte
 Word
 Doubleword
7
Nibble, Byte, Word, Double Word
Nibble, Byte, Word, Double Word
Figure 1-2
8
Kilobyte, Megabyte, Gigabyte, Terabyte
Size (2N
Bytes)
Term
Size (Bytes)
Kilobyte
Megabyte
Gigabyte
Terabyte
1024
1,048,576
1,073,741,824
1,099,511,627,776
Kilobyte, Megabyte, Gigabyte, Terabyte
210
220
230
240
Rounded by
Size (Bytes)
1,000
1,000,000
1,000,000,000
1,000,000,000,000
Table 1-1
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Top Level
Computer Components
CPU
Main Memory


MAR
PC
MBR
IR
I/O AR
Execution
Unit or
ALU
System
bus
Instruction
Instruction


I/O BR
Data
Data
I/O Modules


Buffers


VON NEUMANN ARCHITECTURE
• von Neumann architecture: Programs and data are
stored in memory (stored-memory concept).
• Consists of processor, memory and devices.
• Data are carried along buses between components.
Bus
Processor
Memory
Control
Devices
Input
Cache
Datapath
Output
Registers
11
Random Access Memory (RAM)
 Physically exists as set of microchips installed on plastic
card (memory module)
 Central Processing Unit (CPU) uses RAM like people
use notepad
 Stores binary value so can use it later
 Can read data from RAM to recall value stored earlier
 CPU sends electrical signal over bus (electrical pathway)
to communicate with RAM
12
Random Access Memory (RAM) (cont.)
 RAM uses address for each unique memory location
where byte can be stored
 To write to RAM: CPU sends signal to RAM over the bus
to write (store) value into byte of RAM
 Address in RAM
 Value to be written
 To read from RAM: CPU uses similar process (see
example in Figure 1-3 on next slide)
13
CPU Reads Byte 4 from RAM
The CPU uses the same bus to read the current value of a byte in RAM as it does
to send a message to RAM. The read request lists the address of the particular
byte, asking for its value. RAM returns the binary value stored at that address.
CPU Reads Byte 4 from RAM
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Figure 1-3
Writing Individual Bits in Byte 4 of RAM
RAM circuitry sends a slightly different electrical input to the bits that need to store
a 1 versus a 0 to control the capacitors . Essentially, RAM chooses one of two
inputs to each bit, which results in either a full or partial charge in the capacitor,
which in turn represents either a 1 or 0, respectively.
Writing Individual Bits in Byte 4 of RAM
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Figure 1-4
One Gigabyte RAM Card
Photo of a One Gigabyte RAM Card
16
Figure 1-5
Representing Information Using Bytes of Data
 Data: Focused on bits and bytes
 Information: Focused on meaning and context
 Text Character Sets (character encoding scheme): Lists
all text characters available on computer with matching
binary value
17
Converting Binary 01111011 to Decimal 123
1. Multiply the decimal digit value times the binary value in
each of the eight columns.
2. Add the eight numbers found from the previous step (bottom
row in the table).
Converting Binary 01111011 to Decimal 123
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Figure 1-7
Unsigned Integers in Computers, Various Sizes
Size of
Storage
Range,
From 0
to 2N – 1
Number
of Bits
Byte
8
0 - 255
28 - 1
Word
16
0 – 65,535
216 - 1
Doubleword
32
0 – 4,294,967,296
232 - 1
NOTE: Appendix B, Numeric Reference Tables, includes a table of
decimal numbers 0-255, along with their 8-bit binary equivalent
values.
19
Table 1-2
Permanent Storage for Bits, Bytes
 File Systems – Allow computer to store bytes of single file
in many locations, while still keeping track of them
 Files – Named set of related bytes of data that OS stores as
single entity (based on name) to easily refer to data




Unique name for each file
Keep bytes in order
Can be stored on any kind of physical storage device
Can be copied or moved to other devices and stored there as well
 File types examples





Song (.mp3, .wav)
YouTube video (.swf, .mpeg, .avi)
Text file (.txt, .rtf)
This PowerPoint presentation (.ppt., .pptx)
High-resolution image from space telescope (.png, .jpg)
20
The Process of Storing Files
1. Application knows
addresses in RAM
that hold contents of
document
2. When user clicks
save and names the
file, OS sends file
contents over bus to
storage location
(drive)
3. Drive stores file
Creating a File on Disk
21
Figure 1-9
File Systems and Directories
Directory - Part of file system used to organize files into
hierarchy, keeping similar files together.
Directory Structure: Disk Drive (C:) and DVD Drive (D:)
22
Figure 1-10
Hard Disk Drives





Most common long-term computer storage devices today
Store a lot of data
Do not cost a lot of money
Make data available all the time
Storage topics




Hard Disks vs. Floppy Disks
Hard Disk Drive Internals
Writing Data to Sectors, Tracks
Using Bus to Communicate
23
Hard Disks vs. Floppy Disks
Anatomy of 3.5" Floppy
The magnetic disk rotates
between two liners inside
the plastic jacket.
http://encyclopedia2.thefreedictionary.com/floppy+disk
Internal Image, Floppy Disc
24
Figure 1-14a
Hard Disks vs. Floppy Disks (cont.)
http://www.wdc.com/global/images/overview/en/OV_intdesktop.jpg
Internal Photo, Disk Drive
25
Figure 1-14b
Writing Data to Sectors, Tracks
A platter has many
locations that can hold
magnetic charges.
Physically, these
locations exist in
concentric circles, with
each circle called a
track. A sector refers to
a subset of a track, as
shown in the figure.
Tracks and Sectors in a Single Disk Drive Platter
26
Figure 1-15
Using a Bus to Communicate
 Bus – Electrical pathway between internal components of
computer
 CPU uses bus to connect to hard drive (uses different
electrical circuits to pass control information versus data)
 Bus creates one or more electrical circuits between
motherboard and disk drive
 To send bit value of 0, device varies electrical current in some predetermined way
 To send bit value of 1, device varies electrical current in some other
way
27
Break
Take 15
28
Other Permanent Storage Devices
 Many competing types of permanent storage devices
 Different devices use different mechanisms to read and
write data
 USB Flash Drives
 CD and DVD Drives
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Memory Hierarchy
30
Memory Hierarchy 2
Memory issues
 Faster access time grater cost per bit
 Greater Capacity Smaller cost per bit
 Greater capacity slower access speed
Going down Memory Hierarchy
1.Decreasing cost per bit
2.Increasing capacity
3.Increasing access time
4.Decreasing frequency of access to the memory
by the processor
Key Comparison Points, Permanent Storage
Short
Description
Longer Description
Hard Disk
Drive (HDD)
Internal or
External?
Does the device sit inside the computer, where is
stays, or does it connect externally, so it can be
easily moved between computers?
Both
Removable
Media?
Can you remove the media from the drive, and
insert new blank media to record more data?
No
Solid State?
Solid state means that the device has no moving
parts; moving parts make it more likely to break
over time
No
Key Comparison Points, Permanent Storage
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Table 1-3
Key Comparison Points, Permanent Storage
(cont.)
Short
Description
Longer Description
Hard Disk
Drive (HDD)
Read/Write
Speed vs.
Internal HDD
How fast do reads and writes occur, compared to
an internal Hard Disk Drive (HDD)?
N/A
Price/GB
Compared to
HDD
How much does a typical device cost, per
GigaByte (GB) of storage, relative to a hard disk
drive (HDD)?
N/A
Key Comparison Points, Permanent Storage
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Table 1-3
Key Comparison Points, USB Flash and Hard
Disk Drives
Short Description
Internal or External?
Removable Media?
Solid State?
Read/Write Speed vs. Internal HDD
Hard Disk
Both
No
No
N/A
Price/GB, at Publication, vs. HDD
N/A
*
USB Flash
Drive
External
Yes*
Yes
Slower
More
Expensive
Media cannot be removed from the drive, but the entire drive can be removed from the
computer.
Note: Table information may change over time, but as of publication, USB flash
drives work well for convenience, portability, and low price; but are too slow
and too small to be used to replace a hard disk drive.
Key Comparison Points, USB Flash and Hard Disk Drives
34
Table 1-4
CD and DVD Drives
Compact Disc (CD) and Digital Video Disc (DVD) drives
provide an entirely different class of computer storage as
compared with hard disk drives and USB flash drives.
http://www.samsung.com/us/images/article/heromodule_DVDWriter.jpg
Photo of USB DVD Drive
35
Figure 1-19
Input and Output (I/O)
 Input : Creating information in computer






Typing at keyboard
Clicking with mouse
Talking into computer microphone
Recordings from video security camera connected to computer
Statistics gathered by website
Sales data from grocery store scans
 Output: Presents information to users and for other
purposes
 Computer display showing image or some video
 Computer speakers playing sound
 Printers printing images
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How Keyboards Send Bits to Represent Letters
To physically send bits to the computer, the
keyboard varies the electrical signal over time.
Fro example, to send a binary 1, the keyboard
might use a positive voltage (the current flows in
one direction), and to send a 0, use a negative
voltage (the current flows in the opposite
direction).
Wired Keyboard Connection to a PC System Unit
37
Figure 1-20
How Keyboards Send Bits to Represent Letters
(cont.)
Imagine the user has opened a text editor and is ready to practice typing
“The quick brown fox jumped over the lazy river.” The graphic here
illustrates what happens when the “T” is pressed (requires 2 keys, the Shift
and “t” keys).
Keyboard, Character Map, Bit Transmission, and Storing the Typed Character
38
Figure 1-21
How Keyboards Send Bits to Represent Letters
(cont.)
1. User presses Shift and t character simultaneously for
uppercase “T”
2. Keyboard processor looks at keyboard map to find binary
code associated with uppercase “T”
3. Keyboard sends binary code such as 01010100 (actual
code might be different)
4. CPU processes input using same keyboard map as
keyboard
5. CPU stores newly-arrived input character “T” into RAM,
ready to serve it to active application
6. Application takes over knowing letter “T” had been typed
and using some stipulated logic
39
How Keyboards Know What Key(s) You
Pressed
Question: How does keyboard processor know what key is
pressed? (HINT: Think in terms of simple light switch)
 Consider what happens with simple electrical circuit when
light turned on or off
 Turn light switch on, completes electrical circuit that allows
electrical current to flow and causes bulb to light
 Flip light switch off, switch breaks circuit which stops flow of
electrons which makes bulb go dark
 Think of each keyboard key as separate on/off switches
 Press key, close circuit: Tells keyboard processor what key is
pressed
 Press multiple keys: Processor notices that multiple circuits have
current flowing (e.g., to create an uppercase letter)
40
How Keyboards Send Bits to Represent Letters
Assuming uppercase T is pressed, here is how the current flows from each
pressed key to the keyboard’s processor:
Keyboard basically monitors for pressed
keys and then reacts (notices which electrical circuits have a current). The
processor determines which circuits have current, then the keyboard
processor uses the keyboard map to decode the circuits, and then it sends
the binary code for the character to the CPU.
Current Flow from Each Pressed Key to the Keyboard’s Processor
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Figure 1-22
The Mouse
 Allows control of computer’s actions but in much different
way than keyboard: Point-and-click
 When user moves mouse pointer, OS has list of actions to
take depending on mouse action
 Single click of left mouse button causes OS application window
to become active
 Double click of left mouse button when pointing at icon or file
causes OS to start application or open file
 Single click of right mouse button causes app or OS to display
contextual menu based on where pointer was when click occurred
42
Other Mice
 Wireless mice require no cable connected to mouse,
which makes them more convenient
 Instead of sending bits over cable, mouse uses low-power radio
waves (typically Bluetooth)
 Optical mouse uses light and light sensors to sense
movement of mouse
 Mouse shines light, watches reflections, and senses movement
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The Computer Display





Provides output
Also called computer monitor or screen
Shines light so user can see information on screen
Sits outside system unit, connecting to system using cable
When system powered off, display either shows nothing or
some kind of error message
44
Printers
 Convert computer file to image on paper
 Uses method similar in concept to how display uses pixel
map to create image on screen
 Uses number of dots on paper organized into grid
 Printers identified by how many dots per inch (DPI) they
print in a square inch
 More dots per inch=Better print quality
 Computer has to “translate” from its file to mapping of dots
to print
 Example: Word processor has bytes that represent “The quick
brown fox jumps over the lazy river.” as ASCII stored in RAM
 To print, printer driver translates bytes to correct format to
determine which dots to print on paper to form each letter
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Summary: This Chapter…
 Defined concepts behind bits and bytes
 Described in general terms how computers store data in
Random Access Memory (RAM)
 Explained how computers represent text characters using
bits held in RAM
 Discussed how computer file systems organize data
 Described in general terms how computers store data on
drives
 Explained general steps that occur when a key is pressed
on keyboard
 Described the basic information that a mouse sends to a
computer to move the mouse pointer
 Explained the concepts behind a computer display’s pixel
map, and how computers use bits to represent pixel color
46
Assignment
• Unit 1 Assignment 1: Computer Basics
Review
• Complete Review Questions at the end of
Chapter 1 of the text book
• Print and submit assignment in the next
class.
• Reading assignment: Read chapter 1 and
2 of the text book.
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Unit 1 Lab Activities
•
•
•
•
•
•
•
Complete:
Lab 1.1: Reading Binary
Lab 1.2: Binary Math and Logic
Lab 1.3: Bit and Byte Structure
Lab 1.4: ASCII
Lab 1.5: Creating a File System
Lab 1.6: Gathering System Information
48