1.4 DATA REPRESETATION: BIT, BYTE AND CHARACTER. 


BIT.
A bit (short for binary digit) is the smallest unit of data computer can process. The binary system is a number system that has just two unique digits, 0 and 1 called bits. A bit is represented by the number 1 and 0. These numbers represent the binary system. They correspond to the states of on and off, true and false, or yes and no.

BYTE
Byte is a unit of information built from bits. When 8 bits are grouped together as a unit, they form byte. Bits and bytes are the basis for representing all meaningful information and programs on computers.

CHARACTER
One byte is equal to 8 bits. One byte represents a single character such as the number, letter, or symbol. For example, the capital letter F is represented by binary code 01000110 that can be understood  by the computer system.
Computer does not understand letters or numbers or pictures or symbols. Computer uses a binary system to count as it only recognizas two states that are 0 an 1. Number  9 is represented by binary code 00111001. Eight bits grouped together as a unit are called byte. A byte represents a single character in the computer.
                                         1 byte = 8 bits = 1 character
There are three character codes or coding schemes to represent characters which are ASCII, EBCDIC and Unicode. Each byte contains eight bits. A byte provides enough different combination of 0s and 1s to represent 256 characters.
ASCII is the most widely used binary code for microcomputers (Personal Computer).
EBCDIC was developed by IBM and is used primary for large computer - mainframe and high end server.
The combinations of 0s and 1s are defined by patterns. These patterns are called coding system. The 256- character capability of ASCII and EBCDIC is too small to as Arabic, japanese and Chinese.
The Unicode coding schme is designed to solve this problem. It uses two bytes(16 bits) to represent one character. This gives it the capability for representing 65,536 different characters. This can cover all the world's languages. Unicode is downward-compatible with ASCII, meaning that Unicode can recognizes ASCII characters.
                                                        Unicode
                                      2 bytes = 16 bits = 1character

1.3 INFORMATION PROCESSING CYCLE

input is any data or instructions that we enter into the computer system for processing. There are some common ways of feeding input data into the system, which are: typing on a keyboard and pointing with a mouse.

The processing unit controls all activities within the system. For every instructions, the control unit repeats a set  of four basic operations called the machine cycle(fetch, decode, execute and store


Function of CPU

1. Fetch a program instructions or data item from memory
2. Decode the program instructions into signals that computer can execute.
3. Execute the instructions.
4. Store (return) the result of instructions to the memory
5. Interprets and carries out basic instructions that operate a computer
6. Control unit direct and coordinates operations in computer
7. Arithmetic logic unit(ALU) performs arithmetic, comparison, and logical operations

The central processing unit consist of two part: the control unit (CU) and the arithmetic logic unit (ALU). Each part has specified functions. The control unit tells us rest of the computer system how to carry out a program's instructions. It directs the movement of electronic signals between memory, which temporarily holds data, instructions and processed information, and the arithmetic-logic unit. It also directs these controls signals between the CPU and input and output devices.

Arithmetic-logic unit performs two types of operations: arithmetic and logical. Arithmetic operations are fundamental math operations: addition, subtraction, multiplication, division. Logical operations consist of comparison.

The storage is a location in which data, instructions, and information are saved for future used. Every computer uses storage to hold system software and application software. There are two types of storage, which are primary storage and secondary storage.

Output is data that has been processed into a useful form, called information. There are four types of output, which are texts , graphics, audio and video.   

CHAPTER 2 - COMPUTER SYSTEMS

1.0  System concept

1.1  Define Computer Systems.

Computer is an electronic device, operating under the control of instructions stored its own memory,

• that can accept data (input),
• process the data according to specified rules (process),
• produce results (output),
• and store the results for future use (storage).

Meaning of input, process, output and storage.

1. Input - input is any data and instructions entered into the memory of a computer. There are four types of input which are: text, graphics, audio, and video.
2. Input device - Input device is any hardware component that allows users to enter data and intructions into a computer. Eg: keyboard, mouse, scanner, barcode reader. Also pointing device: mouse, joystick, trackball, touch screen, pointing stick and graphic tablets.'
3. CPU/central processing unit - CPU is an electronic component on a computer's motherboard that interprets and carries out the basic instructions that operate the computer. Eg: intel pentium IV, AMD Athlon, G4.
4. Output - output is data that has been processed into a useful form, called information.
5. Output device - Eg: speaker, monitor, LCD projector, p\printer, plotter.
6. Storage - storage is a location in which data, instructions, and information are saved for future use. Eg: CD ROM, diskette, hard disk.

2.9 FRAUD, COPYRIGHT INFRINGEMENT, THEFT, and ATTACKS.


a) Computer fraud is the crime of obtaining money by deceiving (to trick) people through the use of                computers. There are many forms of computer frauds which include

• e-mail hoaxes (hoax- an attempt to make people believe something that is not true)
• program fraud
• investment schemes
• sales promotion
• claim of expertise on certain fields

b) Copyright infringement is defined as a violation (an action to break the law) of the rights secured by a copyright. Copyright is the legal right to be the only producer seller of a book, song and film. Infringement of copyright occurs when you break the copyright laws such as copying movies, software or CD's illegally - selling pirate software. Piracy is the crime of illegally copying and selling books, tapes, videos, computer programs.

c)Computer theft is the defined as the unauthorized used of another person's property. Example of computer thefts are

• transfer of payment to the wrong accounts
• get online materials with no cost
• tap (memasuki) into the data transmission lines

d)Computer attack is defined as any activities taken to disrupt (causing problems so that something cannot continue normally) the equipment of computers systems, change processing  controls and corrupt stored data. Corrupt - when data on a computer becomes corrupt, it is spoilt and cannot be properly used because it has become changed in wrong ways.

Computers attack can be in the forms of

• Physical attack that disrupt the computer facilities or transmission lines.
• An electronic attack that

COMPUTER CRIMES

2.8 Need for cyber law

In today's highly digitalized world, almost everyone is affected by cyber law. Let us take a few examples: 

• Almost all companies extensively depend upon their computer networks and keep their valuable data in electronic form.
• Government forms including income tax returns, company law forms etc are now filled in electronic forms.
• most people are using email, cell phones and SMS message for communication.

Examples of cyber abuse on the users

• sending a computer virus via e-mail.
• harassment through e-mail.
• hacking into school's database to charge your examination results.

Why we need cyberlaw

1. Criminal activities can be brought to justice. If any criminal happen to customers, they can bring who.
2. Cyber Laws are made to force people to be good, because individuals are more controlled by their passion and alone can't make them good, so laws were created to scare people in being 'good'.
3. Customer is made to feel secure because bank protects their money.
4. To give protection against the misuse of computers and computer criminal activities such as unauthorised use of programmes, illegal tranmission of data or messages over computers, hacking and cracking of computer systems and networks.

2.7  PROCESS OF FILTERING to control access to controversial contents.

The method of choice to limit access on the Internet is to filter either by

• keyword blocking.This method uses a list of banned word objects terms such as xxx, sex and nude. As the page is downloading, the filter searches for any these words. If found, it will blocked the page completely, stop downloading the page, block the banned words and even shut down the browser.
• Site blocking. This method use software to list the web sites that will be blocked by using software. The software also prevents user from being access the web sites on list.
• Web rating system. Web sites are rating in terms of nudity, sex violence and language. The web sites rates can be done by setting the browser to only accept pages with certain level of ratings.

CONTROVERSIAL CONTENTS AND CONTROL

2.6  Effect of controversial contents (PORNOGRAPHY and SLANDER) on society :
      Pornography
Pornography is any form of media or material (like books, video or photos) that show erotic behaviour and intended to cause sexual excitement. The effects of pornography on society are :

• Can lead to criminal acts such as exploitation of women.
• Can lead to sexual addiction.
• Can develop lower moral values towards other people.
• Can erode good religious, cultural, behaviours and beliefs.

        Slander
Slander is a false spoken statements about someone, intended to damage his or her reputation. The effects of slander on society are :

• Can develop society that disregards on honesty and truth
• Can lead to bad habits of spreading rumors and untruth
• Can cause people to have negative attitudes towards another person.