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Review- IT1010
2With thanks to Dr. Haipeng Guo and Dr. Judy Feng
LaTeX
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What is TeX? TeX is a typesetting system ( 排版系统 )
written by Donald E. Knuth in 1976, who says that it is “intended for the creation of beautiful books — and especially for books that contain a lot of mathematics”
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What is LaTeX? LaTeX is a free high-quality
document processing system that is based on TeX
LaTeX was originally written by Leslie Lamport in the 1980s
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Why LaTeX ? It is the premier typesetting package
in the world! It's free!!! It's available for many machines
(Linux, Mac, Windows) LaTeX files are ASCII
Therefore they are very portable You can use the editor of your choice
(Some people even use MS Word)
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Why LaTeX ? The typesetting is better
especially the maths Style changes are neater in LaTeX
Style files for many periodicals exist Many MS Word users don't use styles or
templates, so there's a limit to what they can do
LaTeX is extensible If you want a new feature, find a free
add-on or write one yourself
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Disadvantages LaTeX encourages (almost insists
on) structured writing and the separation of style from content This is not the way that many people
(especially non-programmers) are used to working
Without a WYSIWYG (What You See Is What You Get), it's not always easy to find out how to do things
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“Hello World” Example Suppose we want to produce the
following document:
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In MS Word To produce this in most typesetting or
word-processing systems, the author would have to decide what layout to use, so would select (say) 18pt Times Roman for the title, 12pt Times Italic for the name, and so on
This has two results: Authors wasting their time with designs A lot of badly designed documents!
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In LaTeX\documentclass{article}\title{Introduction to LaTeX}\author{Bill Gates}\date{November 2007}\begin{document}
\maketitle Hello world!
\end{document}
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Or In English This document is an article Its title is An Introduction to
LaTex Its author is Bill Gates It is written in November 2007 The document consists of a title
followed by the text Hello world!
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A Quick Start (0) 5 Steps involved in creating LaTeX
documents1.1. EditingEditing (to create a .tex source file)
2.2. CompilingCompiling (to generate a .dvi file)
3.3. ViewingViewing (to view the file on the screen)
4.4. PrintingPrinting (to generate a postscript file, .ps)
5.5. GeneratingGenerating a pdf file
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LaTeX Document Structure% A simple article to illustrate document % structure.
\documentclass[12pt]{article} \usepackage{times} \begin{document} …… \end{document}
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Document Classes At the top of the file you will have a line
something like \documentclass[12pt]{article}
It determines the font size (12pt) and document class (article)
The document class specifies the type of document you intend to write
It is associated with a class file, .cls Valid document classes include article,
report, book, letter
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Packages \usepackage{times}
A LaTeX package contains a set of commands that are not built into the core of LaTeX, but useful for special purposes.
To find out what commands a package provides (and thus how to use it), you need to read the documentation.
There exist hundreds of packages and they are all free!
Commonly used packages in mathematics Amsmath, amssymb, amsthm
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%: comments \documentclass[12pt]{article}
The type of document we want to produce: article Other classes that exist are book, report, thesis etc 12pt: the font
\usepackage{times} It tells Latex to utilize some external packages that
contain some useful commands \begin{document} … \end{document}
LaTeX Document Structure
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Top Matter \title{How to Structure a \LaTeX{}
Document} \author{ Bill Gates\\ Computer Science
and technology Program,\\ United International College,\\ Zhuhai, China\\ \texttt{[email protected]}} \date{\today}
\maketitle
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Output
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Abstract\begin{abstract} In this article, I shall introduce to you \
LaTeX{}, a typesetting software that is much better than Microsoft Word. I shall discuss some of the fundamental topics in producing a structured document. This document itself does not go into much depth, but is instead the output of an example of how to implement structure.
\end{abstract}
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Output
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Sectioning Commands \section{Introduction}
This section's content... \section{Structure}
This section's content... \subsection{Top Matter}
This subsection's content... \subsubsection{Article Information}
This subsubsection's content...
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Output
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Bulleted List \begin{itemize}
\item \texttt{\textbackslash address} - The author's address. Use the new line command (\texttt{\textbackslash\textbackslash}) for line breaks.
\item \texttt{\textbackslash thanks} - Where you put any acknowledgments.
\item \texttt{\textbackslash email} - The author's email address.
\item \texttt{\textbackslash urladdr} - The URL for the author's web page.
\end{itemize}
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Output
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The Bibliography \begin{thebibliography}{9}
\bibitem{lamport94} Leslie Lamport, \emph{\LaTeX: A Document
Preparation System}. Addison Wesley, Massachusetts, 2nd Edition, 1994.
\end{thebibliography}
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Citation In the text, This small document is designed to illustrate
how easy it is to create a well-structured document within \LaTeX\cite{lamport94}. You should quickly be able to see how the article looks very professional, despite the content being far from academic. Titles, section headings, justified text, text formatting etc., are all there, and you would be surprised when you see just how little markup was required to get this output.
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The Tabular Environment \begin{tabular}{ l c r } 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \\
\end{tabular}
\begin{tabular}{|l|l|} \hline stuff & stuff \\ \hline stuff & stuff \\ \hline \end{tabular}
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Mathematics Environments text formulae
\begin{math}...\end{math} $...$
displayed formulae \begin{displaymath}...\end{displaymath} \[...]\ \begin{equation}...\end{equation}
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Fraction LaTeX sourceLaTeX source
$\frac{x+y}{x-z}$ $\frac{\frac{1}{x} + \frac{1}{y}} {y-z}$
OutputOutput
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Powers and Indices LaTeXLaTeX sourcesource
$x^2$ $x^{2n}$ $X_i$ $X_{ij}$
OutputOutput
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Roots LaTeXLaTeX sourcesource
$\sqrt[3]{4xy^2}$ OutputOutput
What is the output of $\sqrt{\frac{a}{a+b^2}}$?
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Performing Calculation A distinguishing feature
Otherwise it is not more than a large table Formula calculations
Must begin with equal sign “=” Performs calculations and displays the result Includes cell addresses Visible in the cell entries of the formula bar after
execution Point mode
Enter a formula without typing cell addresses By clicking cells or using arrow keys
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Formula Calculation Example
Calculating the sub total for a number of textbooks.
The formula multiplies the quantity and price of each textbook and adds them together
Formula is shown in the formula bar after
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Performing Calculation Cell addressing
Identified by the column and row, e.g. B6 Records cell addresses in formulas in three ways Relative referencing
Calling cells by just their column and row labels Cell addresses will be changed when copy them
e.g. C1 "=(A1+B1)" C2 "=(A2+B2)" Absolute referencing
Accomplished by placing dollar signs "$"
e.g. "=($A$1+$B$1)" Mixed referencing
Only the row or column is fixed.
e.g. "=(A$1+$B2)"
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Performing Calculation Reference operators refer to a cell or group
of cells • Range operator “:”
• TWO cell addresses separated by a colon • Refers to ALL the cells included in the reference
e.g. “A1:C3” includes A1, A2, A3, B1, B2, B3, C1, C2, and C3.
• Union operator “,”• Two or more cells separated by a comma • Refers ONLY to the cells (rather than a range) • e.g. “A7,B8,C9” includes only cells A7, B8, and C9
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Performing Calculation Linking worksheets
Use the value from a cell in another worksheet
Format: "sheet_name!cell_address"
e.g.: "=A1+Sheet2.A2"
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Performing Calculation – Functions
Functions Allow you to quickly perform calculations More efficient way than typing formula
formula: "=D1+D2+D3+D4+D5+D6+D7+D8+D9+D10" function: "=SUM(D1:D10)"
Format for using functions Use an equal sign to begin a formula Specify the function name Enclose arguments within parentheses Use a reference operator (a comma “,” or colon
“:”) to separate arguments
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FunctionsFunction Example Description
SUM =SUM(A1:A100) finds the sum of cells A1 through A100
AVERAGE =AVERAGE(B1:B10)finds the average of cells B1 through B10
COUNT =COUNT(B1:B10)finds the number of items from cells B1 to B10
MAX =MAX(C1:C100)returns the highest number from cells C1 through C100
MIN =MIN(D1:D100)returns the lowest number from cells D1 through D100
SQRT =SQRT(D10)finds the square root of the value in cell D10
TODAY =TODAY()returns the current date (leave the parentheses empty)
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Performing Calculation –Functions
The Sum icon
Automatically adds a column of numbers Highlight all cells above current cell and add For empty column, Sum adds the row values
Recalculations Automatically recalculate when changing cell
entries Tools > Cell Content > Recalculate
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Performing Calculation –Sort Sort on one column
Sort Ascending button
Sort Descending button Sort on multiple columns
Highlight all columns Data > Sort Select 1st column (key
word) in Sort By field Select 2nd and 3rd column
in Then By field. Choose Header row or No
header row box
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Computer Literacy What is computer literacy?
having knowledge and understanding of computers and their uses
refers to the ability to use applications rather than to program
Why is computer literacy important? Computers are everywhere nowadays One study alleges that “…those with less access
to technology are less successful!”
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What is a Computer? A computer is
is an electronic machine or deviceexecuting the instructions in a program
A computer can accept data, manipulate or process the data, produce results, and store the results
input process
outputstore
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Data and Information Data
Raw facts, figures, and symbols
Information organized,
meaningful, and more useful
(to people)
data
information
computer + program
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Computer ComponentsHardware: the physical parts of the computer Hardware: the physical parts of the computer
output devices
storage devices
input devices
system unit
CPU memory
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Why is a Computer Powerful?
1) Speed A computer can do billions of actions per second
2) Reliability and Accuracy Failures are usually due to human error, one way or another
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4) Communications Computers connected with each other can share resources
3) Storage A computer can keep huge amounts of data
Why is a Computer Powerful?
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Storage Devices
Hard disk
USB flash disk
CD/VCD/DVD drive
floppy disk
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Network and Internet A network is a collection of computers
and devices Networks allow users to share resources
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Types of Computers Personal Computers (PCPCs)
Desktop computers Laptop or notebook computers handheld computer personal digital assistant (PDAPDA)
Servers Workstations Mainframes Supercomputers
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What is a LAN? Local Area Network A group of computers and devices In a limited geographic area
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Computer SoftwarePrograms that give instructions
to the hardware about what to do and how to do it
System Software Programs that perform system
tasks For example: Operating Systems
(Windows, Linux, MacOS)
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Computer Software Application Software
Programs that perform user-specific tasks
E.g. word processing, spreadsheets, databases, web applications …
Software is (usually) written by programmers Why “usually”?
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An Information System Besides computer hardware and computer
programs, an information system also includes the procedures, documentation, and management to make a computer system run smoothly Hardware Software Data People Procedures
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Applications for a SOHO user
Small Office Home OfficeSmall Office Home Office
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Alan Turing (1912-1954)
An English mathematician, logician, cryptanalyst, and computer scientist
Time magazine named Turing as one of the 100 important people of the 20th century for his role in the creation of the modern computer
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Turing Machine In 1936 Turing demonstrated an
imaginary machine that could mimic human reasoning
A fairly simple device capable of scanning, reading or writing data and instructions on a tape of theoretically infinite length
Turing machine provides an abstract model of computation
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Turing Machine A Turing machine has a tape of infinite length,
a read-write head, and a control unit. The tape is divided into squares The head can move one position left or right.
It can also read or write 0/1 on the tape. The control unit contains instructions that tell
the Turing machine what to do next given its current state of the Turing machine and the symbol at the current position
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Ada Lovelace: the first programmer Byron's daughter
De De Morgan's student
Specified a method for calculating Bernoulli numbers with Charles Babbage's Analytic Engine
Recognized by historians as the world's first computer programmer
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Generations of Computers Generation 1 (1945-1953): Vacuum Tube
Computers Generation 2 (1954-1965): Transistor
Computers Generation 3 (1966-1980): IC (Integrated
Circuits) Computers Generation 4 (1980-present): VLSI (Very
Large Sacle IC) Computers
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Why Hexadecimal? Hexadecimal is meaningful to humans,
and easy to work with for a computer Compact
A BYTE is composed of 8 bits One byte can thus be expressed by 2
digits in hexadecimal 11101111 EF (11101111)2 EFh
Simple to convert them to binary
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Binary to Decimal
Convert (10010011)2 to decimal:
(10010011)2 = 1 * 27 + 1 * 24 + 1 * 21 + 1 * 20
= 128 + 16 + 2 + 1 = (147)10
Conversions Between Number Systems
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Conversions Between Number Systems Hexadecimal to Decimal
Convert 21Fh to decimal:
21Fh = 2 * 162 + 1 * 161 + 15 * 160
= 512 + 16 + 15 = (543)10
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Conversions Between Number Systems
Octal to Decimal
(32)8 = (?)10
What’s wrong?
(187)8 = 1*64 + 8*8 + 7*1
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Conversions
Decimal to binary Hexadecimal OctalQuotient Remainder 2) 28 ( 0 16) 28 ( C 8) 28 ( 4 2) 14 ( 0 16) 1 ( 1 8) 3 ( 3 2) 7 ( 1 0 0 2) 3 ( 1 Reading the remainders from
2) 1 ( 1 bottom to top, we have 0 (28)10=(11100)2 (28)10=(1C)16 (28)10=(34)8
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One More ExampleConvert 14710 to binary
So, 14710 = 100100112
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Conversions Between Number Systems
Decimal to Base rr Same as Decimal to Binary Divide the number by rr Record the quotient and remainder Divide the new quotient by rr again ….. Repeat until the newest quotient is 0 Read the remainder from bottom to top
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Exercises
Convert 19910 to binary Convert 25510 to binary Convert 25510 to hexadecimal Convert 2558 to decimal Convert 12316 to decimal
Please show your steps of conversion clearlyPlease show your steps of conversion clearly..
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Conversions Between Power-of-2 Radices
Because 16 = 24, a group of 4 bits is easily recognized as a Hexadecimal digit
And a group of 3 bits is easily recognized as one Octal digit
To convert a Hex or Octal number to a binary numberRepresent each Hex or Octal digit with 4 or 3 bits in
binary
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Convert a binary number to Hex or Oct number
Conversions Between Power-of-2 Radices
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Basic Arithmetic Operations with Binary Numbers
Rules for Binary Addition 1+1=0, with one to carry to the
next place
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Example
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Example
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Basic Arithmetic Operations with
Binary Numbers
Rules for Binary Subtraction 1 - 0 = 1 1 - 1 = 0 0 - 0 = 0 0 - 1 = 1 … borrow 1 from the
next most significant bit
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Example
minuend
subtrahend
difference
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Exercises00011010 + 00001100 = ?
00110011 - 00010110 = ?
00101001 × 00000110 =?
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Data Representation Data comes in many forms
Numbers: 235, 11.01, -24, … Text: “hello, world!” “ 你好！” Audio: .mp3 Images and graphics: .bmp, gif, JPEG Video: .avi
All of the data is stored in computers as binary digits Data must be represented in a way that
Captures the essence of the information And in a form that is convenient for computer
processing
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Analogue and Digital Information
Information can be represented in one of two ways: analogue or digital
Analogue data: A continuous representation, analogous to the actual information it represents
Digital data: A discrete representation, breaking the information up into separate elements
A mercury thermometer is an analogue device The mercury rises in a continuous flow in the
tube in direct proportion to the temperature
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Analogue Data A mercury thermometer is an analogue
device. The mercury rises in a continuous flow in the tube in direct proportion to the temperature.
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Binary Representation In general, n bits can represent 2n things
because there are 2n combinations of 0 and 1 that can be made from n bits
Note that every time we increase the number of bits by 1, we double the number of things we can represent
Questions: How many bits are needed to represent 128 things? How many bits are needed to represent 67 things?
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Binary Representation
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Representing Text A text document can be decomposed into
chapters, paragraphs, sentences, words, and ultimately individual characters
To represent a text document in digital form, we simply need to be able to represent every character that may appear In English, “a, b, …, z, A, B,…Z”
The general approach for representing characters is to list them all and assign each a binary string ‘a’ (01100001)2 (97)10 61h
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Character Set A character set is a list of
characters and the codes used to represent them
By agreeing to use a particular character set, computer manufacturers have made the processing of text data easier
ASCII, Unicode, etc.
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ASCII ASCII stands for American Standard
Code for Information Interchange The ASCII character set originally
used seven bits to represent each character, allowing for 128 unique characters
Later ASCII evolved so that all eight bits were used which allows for 256 characters (Extended ASCII)
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ASCII Note that the first 32 characters
in the ASCII character chart do not have a simple character representation that you could print to the screen
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Unicode Character Set Extended version of the ASCII character
set is not enough for international use The Unicode character set uses 16 bits per
character Therefore, the Unicode character set can
represent 216, or over 65 thousand, characters Unicode was designed to be a superset of
ASCII The first 256 characters in the Unicode
character set correspond exactly to the extended ASCII character set
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Representing Audio Information We perceive sound when a series of air
compressions vibrate a membrane in our ear, which sends signals to our brain
A stereo sends an electrical signal to a speaker to produce sound
This signal is an analogue representation of the sound wave
The voltage in the signal varies in direct proportion to the sound wave
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To digitize the signal we periodically measure the voltage of the signal and record the appropriate numeric value A process called sampling
In general, a sampling rate of around 40,000 times per second is enough to create a reasonable sound reproduction
Representing Audio Information
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Audio Formats WAV, AU, AIFF, VQF, and MP3
MP3 is dominant MP3 is short for MPEG (Moving Picture Experts
Group) audio layer 3 file MP3 employs both lossy and lossless compression First it analyzes the frequency spread and
compares it to mathematical models of human psychoacoustics (the study of the interrelation between the ear and the brain), then it discards information that can’t be heard by humans
Then the bit stream is compressed to achieve additional compression
Representing Audio Information
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Representing Colour Colour is our perception of the
various frequencies of light that reach the retinas of our eyes
Our retinas have three types of colour photoreceptor cone cells that respond to different sets of frequencies
These photoreceptor categories correspond to the colours of red, green, and blue
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Representing Colour Color is often expressed in a computer
as an RGB (red-green-blue) value, which is actually three numbers that indicate the relative contribution of each of these three primary colours
For example, an RGB value of (255, 255, 0) maximizes the contribution of red and green, and minimizes the contribution of blue, which results in a bright yellow
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Representing Images and Graphics The amount of data that is used to
represent a colour is called the colour depth
HiColour is a term that indicates a 16-bit color depth Five bits are used for each number in an RGB
value and the extra bit is sometimes used to represent transparency
TrueColour indicates a 24-bit colour depth Each number in an RGB value gets eight bits
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Digitized Images and Graphics Digitizing a picture is the act of representing
it as a collection of individual dots called pixels
The number of pixels used to represent a picture is called the resolution
Storage of image information on a pixel-by-pixel basis is called a raster-graphics format
Several popular raster file formats including bitmap (BMP), GIF, and JPEG
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What is Cyberspace? 'Cyberspace' is a term coined by
William Gibson, author of 'Neuromancer'
It is the imaginary space we pass through when 'surfing' the Internet
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What is Cyberspace? “the global domain of electro-
magnetics accessed through electronic technology and exploited through the modulation of electromagnetic energy to achieve a wide range of communication and control system capabilities”
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Cyberspace in the Real World
We are at the dawn of Cyberspace in the Real World
We can already see how Cyberspace affects our day-to-day lives
Laws have been written just for Cyberspace! As mobile devices become faster, easier to
use, more advanced and cheaper, Cyberspace will become even more of a real-world reality
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Cyberspace Today Gibson's term has now become a reality,
thanks to improvements in:
Communication Networks (faster Internet)
Hardware (faster, bigger storage) Software (allows for complex applications)
We are always pushing the boundaries of what we can achieve with the technology available
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Affecting Business Thomas L. Friedman outlines the affect
Cyberspace (and what it offers) in his book 'The World is Flat'
He describes how it affects us as individuals, but more importantly how it has changed the face of businesses worldwide
China and India are two countries he focuses on in particular
The book is available in many languages, including Chinese
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Computer Hackers Creating software and sharing it with
each other Placing a high value on freedom of
inquiry; hostility to secrecy Information-sharing as both an ideal and
a practical strategy Distaste for authority Playful cleverness, taking the serious
humorously and their humour seriously
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Hacker vs. Cracker 5. “[deprecated] A
malicious meddler who tries to discover sensitive information by poking around. Hence `password hacker', `network hacker'. The correct term is {cracker}.”
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Types of Cracker There are three types of Cracker:
1.Black Hat Crackers – Crack banks accounts, steal money, identities, documents
2.White Hat Crackers – Computer Security Experts
3.Grey Hat Crackers – In between black and white – will work for money, or to show off their skills
Crackers are technically also Hackers, but not all Hackers are Crackers
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GNU & OpenSource/FreeSoftware GNU – (GNU is not UNIX)
The Free Software movement is headed by the Free Software Foundation, a fund-raising organization for the GNU project
Free software VS Open source software
- Within the Linux community, there are two major ideological movements at work.
-The Free Software movement (which we'll get into in a moment) is working toward the goal of making all software free of intellectual property restrictions. Followers of this movement believe these restrictions hamper technical improvement and work against the good of the community.
-The Open Source movement is working toward most of the same goals, but takes a more pragmatic approach to them. Followers of this movement prefer to base their arguments on the economic and technical merits of making source code freely available, rather than the moral and ethical principles that drive the Free Software Movement. (source codes are opened)
http://www.slackbook.org/html/introduction-opensource.html http://www.gnu.org/philosophy/free-software-for-freedom.html
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Open source software GIMP OpenOffice Linux LaTex Joomla MySql . .
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What is a LAN? Local Area Network Network in limited geographical area
such as home or office building
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What is a WAN? Wide Area Network Network that covers large a geographical
area using many types of media
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What is the Internet? A network of computer networks
worldwide The Internet is world’s largest WAN Also called the information highway,
the net, or cyberspace
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Connecting to the Internet At home
Through Phone modem Through DSL / ADSL Through Cable modem
At office Through LAN
Wireless connection Through hotspots
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Internet Service Provider (ISP)
User PC
Network Access Point
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How the Internet works Every computer connected to the
Internet must have a unique address. This is called the IP address. IP stands for Internet Protocol
5.6.7.81.2.3.4
Internet
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IP Address An IP address can be split into
network address, which specifies a specific network
host number, which specifies a particular machine in that network
118
Domain Name System (DNS) A hostname consists of the computer
name followed by the domain name uic.edu.hk is the domain name
A domain name is separated into two or more sections that specify the organization, and possibly a subset of an organization, of which the computer is a part
Two organizations can have a computer named the same thing because the domain name makes it clear which one is being referred to
119
Domain Name System The very last section of the domain is
called its top-level domain (TLD) name
120
Client/Server ModelAll of the machines on the Internet are either servers or clients
Web server, e-mail server, DNS server, ftp server, game server……
121
How data travels the Internet Messages are divided into fixed-sized,
numbered packets Network devices called routers are used
to direct packets between networks
122
Routers
Routers determine the path between you and an Internet server
123
Network Protocols Network protocols are layered such that
each one relies on the protocols that underlie it
Sometimes referred to as a protocol stack
124
TCP/IP TCP stands for Transmission Control
Protocol TCP software breaks messages into
packets, hands them off to the IP software for delivery, and then orders and reassembles the packets at their destination
IP stands for Internet Protocol IP software deals with the routing of
packets through the maze of interconnected networks to their final destination
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High-Level Protocols Other protocols built on the
foundation established by the TCP/IP protocol suite Simple Mail Transfer Protocol (SMTP) Post Office Protocol version 3(POP3) File Transfer Protocol (FTP) Telnet Hyper Text Transfer Protocol (http)
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Operating Systems A set of programs containing instructions
that maintain and manage the computer resources, such as CPU, memory and input/output devices
Provide an interface through which the user can interact with the computer
The core of a computer’s system software
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Who Creates Computer Software?
Programmers High-level language, easy for humans
C++, Java, etc Low-level language, used by CPU
Machine language Compiler
Translate high-level language into low-level language
129
History of Operating Systems Multiprogramming Systems
allow several executing programs to be in memory concurrently
Timesharing system permits many users to share the same
CPU the CPU switches between user
sessions very quickly, giving each user a small slice of processor time
130
Start the Computer What is booting?
Cold boot Turning on computer that has been powered off
Warm boot Restarting computer that is powered on
Process of starting or restarting a computer
131
Functions of an Operating System?
monitor performance
provide a user interface
provide file management and other utilities
establish an Internet connection
control a network
administer security
start the computer manage programs
schedule jobs and configure devices
manage memory
132
GUI Graphical User Interface
User interacts with menus and visual images such as icons and buttons
133
Memory Management Optimizing use of random access memory (RAM) With virtual memory (VM), portion of hard disk is
allocated to function as RAM This process is called paging When an OS spends much of its time paging, instead
of executing application software, it is said to be thrashing
134
Provide File Managment File System: Hierarchical Directories
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Windows File naming: four parts Drive Path File name File type (extension)
C:\Windows\System\WinTrust.hlp
Provide File Managment
136
Types of Operating System Stand-Alone Operating Systems
works on a desktop computer, notebook computer, or mobile computing device
Network Operating Systems designed specifically to support a network
Embedded Operating Systems Found on most mobile computers, PDAs,
and other small devices
137
Name of OS Unix MS windows –(95, 98, me, xp,…) Mac OS Linux OS/2 . .
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An Introduction to HTML
The most common file-type used to present information on-line is HTML.
Other file-types commonly found on-line include:
MP3, JPG, GIF, PHP, CFM, ASP, HTM, PNG, AVI, MP4, SWF, ICO, ASPX and more![4]
HTML stands for Hypertext Mark-up Language
140
The HTML Code Every HTML file starts with '<html>' and
ends with '</html>'
There are then two main sections to the file:
<head> ... </head>
<body> ... </body>
At any point within the code we can (and should!) write comments, like so:
<!-- this is a comment – for code-view only! -->
141
HTML Lists There are two types of list: ordered lists
('ol') and unordered lists ('ul').
'li' stands for list item
<ol>
<li>This is a list item</li>
<li>This is <strong>another
item!</strong></li>
</ol>1. This is a list item
2. This is another item!
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What is a CMS? CMS stands for Content Management
System.
It is literally a system designed to help you manage content.
Found on-line, they fall under the general term 'web site'
Content Management Systems are used by all kinds of people and organisations, including:
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Limitations of File-based Approach Separated files redundancy in
defining and storing data Difficult to capture inter-file
relationships Labor intensive Difficult to maintain data integrity Program-data dependency
Solution: database approach
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What is a database?
Add, change,
and delete data
Add, change,
and delete data
CreatedatabaseCreate
databaseSort and
retrieve data
Sort and
retrieve data
Createforms and
reports
Createforms and
reports
Database software allows you to
Database software allows you to
Collection of related data organized so
you can access, retrieve, and
use it
Collection of related data organized so
you can access, retrieve, and
use it
Database software also called database management system
(DBMS)
Database software also called database management system
(DBMS)
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Database Management System (DBMS)
Examples: DB2, SQL Server, Oracle, Sybase, MySQL
The management software that provides some convenient ways to the users to manipulate (add, update, delete), retrieve and present the data
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Data Model Every database or DBMS is based
on a specific data model, which consists of rules and standards that define how the database organizes data, and how users view the organization of the data
The most popular data model: Relational Model
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Relational database A relational database stores all its
data in tables The relationships among data
items are also stored in tables All operations on data are done on
the tables themselves or produce another table as the result
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Table
The Movie table contains 10 rows (movies).(ref; record)
Each record has 4 columns (attributes of movies) (ref ; field) MovieID, Title, Genre, Rating
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Records and Fields A table is a collection of records
A record is a collection of related fields
Each field of a database table contains a single data value
Each record in a table contains the same fields
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The Hierarchy of Data
Database contains files (tables) file contains records record contains fields field contains characters
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Relationships When a customer rents a movie, there is
a “rents” relationship between the person and the movie
We can use a table, Rents, to contain information about this relationship
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Relationships When we need data about the customer,
we use CustomerID stored in the Rents table to look up the customer's detail data in the Customer table
Address
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Relationship When we need data about the movie, we
use MovieID stored in the Rents table to look up the movie's detail data in the Movie table
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Relationship This is the basis of relational database.
Relational database is based on the idea that objects (tables) of a database are connected or related so they can exchange information
This exchange of information is made possible by defining relationships among objects (tables) of a database
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Relationship The “rents” relationship is called a
one-to-many relationship One customer many movies One movie only one customer
Types of relationships: one-to-one one-to-many many-to-many
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Operations on Data Adding records
when you obtain new data Modifying records
Correct inaccurate data Update old data
Deleting records When record no longer is needed Some programs remove record immediately, others
flag the record Validating Data
to enhance Data integrity: the degree to which data is correct
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File System vs DB Reduce data redundancy Improve data integrity:
DBMS performs validity check to help ensure the entered data is correct.
Also, the database approach reduces the possibility of introducing inconsistencies.
Share data Easier access Reduce development time More secure
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Data Validation What is validation? Process of comparing data with a set of rules to
find out if data is correct Reduce data entry errors and enhance data
integrity before program writes data on disk
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Structured Query Language (SQL)
A database language for managing relational databases
It includes statements to specify database schemas add, modify, and delete database
contents query the database to retrieve
specific data
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Create a new table To create a new table, we
need to specify1. the table name 2. Name of each field3. size of each field 4. data type of each field 5. the primary key
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The SQL statementcreate table Customer ( CustomerID numeric primary key, FirstName text(20), Surname text(20), Address text(100), CreditCardNumber text(16))
This statement creates the Customer table
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Add New Datainsert into Customer values (
9876,
“John”, “Smith”, “602 Green Street”, “2120 9873 0976 2445”
)
This statement inserts a new record into the Customer table
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What is Image Processing?
Image processing is the storage, management and manipulation of images
Images could be photographs, or graphics
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Adding Text Click the font button to add text
Select from the fonts on your computer, change the size and justification
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4 Primary Issues of Computer Ethics
1. PrivacyPrivacy : the right to be left alone when you want to be. It concerns the collection and use of data about individuals
2. AccuracyAccuracy : relates to the
responsibility of those who collect information to ensure that the information is correct
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3. PropertyProperty : relates to ownership and rights to the information or software
4. AccessAccess : relates to the responsibility of those who have data to control and who is able to use that data
4 Primary Issues of Computer Ethics
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Denial of Service (DoS) Attack Like a worm, it attempts to slow down
or stop a computer system or network Unlike a worm, it can self-replicate A DoSDoS attack floods a computer or
network with requests for information and data.
The targets of these attacks are InternetInternet ServiceService ProvidersProviders (ISPISPs) and specific web sites
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Protection DRM
Digital Rights Management can protect from stealing intellectual goods
Firewalls A Security plan for Organizational Level
A Security plan for Individual Level
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DRM DDigital RRights MManagement Access control technologies used by
hardware manufacturers, publishers and copyright holders to limit usage of digital media or devices. allows the issuer of the media or file to
control in detail what can and cannot be done
can limit the number of viewings, number of copies of the intellectual contents
