Computer Crime

• Software Piracy
• Protections from Piracy 

Software Piracy: 

• Software piracy – the illegal copying of software programs – is the biggest legal issue affecting the computer industry.
• Piracy is of greatest concern to developers of commercial software, or programs that must be purchased before using.
• Piracy is less of a concern for shareware makers, whose programs must be registered but not always purchased. 
• Piracy is not a concern for freeware, which is software that can be freely distributed by anyone.

Protections from Piracy: 

Various forms of copy protection have been used to discourage piracy, including:

•  Installation diskettes that record the number of times the software is installed.
• Hardware locks, without which the program cannot function.
• Passwords, serial numbers, or other codes required for installation.

Small History of Windows-OS

Windows 3.x :

• Windows 3.0, 3.1, and 3.11 are called the Windows 3.x family.
• Windows 3.x brought a GUI and multitasking capabilities to PCs running DOS.
• Windows 3.x is an operating environment because it ran on top of DOS, which was the actual OS.

Windows NT: 

• To work on most PCs at the time of its release.
• Microsoft issued two versions of Windows NT—Windows NT Workstation and Windows NT Server. Microsoft's Windows NT was meant as a replacement for DOS, but was too resource-intensive.
• NT is a very powerful and robust OS, resistant to system crashes. 

Windows 95 and 98: 

• An improved user interface, and enhanced file system performance, among others. Windows 95 was Microsoft's first true GUI-based, 32-bit operating system for Intel PCs.
• Windows 95 supports multitasking and can run older DOS and Windows 3.x programs.
• Windows 98's  features include advanced Internet capabilities.

Windows 2000: 

• Windows 2000 features the same interface and features of Windows 98, with the file system, networking, power, and stability of Windows NT.
• Several versions of Windows 2000 are available, each targeting a specific user or computing environment, from home PCs to large enterprise networks. 

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Smart OS-Linux

• Linux is a recently developed version of UNIX, which is available for free or at a very low cost from various sources.
• Linux is a very powerful 32-bit OS that supports multitasking, multiple users, networking, and virtually any application.
• Linux can run on nearly any type of computer.
• Because of its power and openness, Linux is attracting many users, including students, teachers, Internet service providers, and others.
  

Factors Affecting Processing Speed

• Registers
• RAM
• The System Clock, 
• The Bus
• Cache Memory

Registers: 

• The CPU contains of small memory areas:called registers,which store data and instructions while the CPU processes them.
• The size of the registers determines the amount of data with which the computer can work at a one time.
• Today most PC`s have 32-bit registers,mean the CPU can process four bytes data at one time.Register sizes are rapidly growing to 64 bits.

RAM: 

• The amount of RAM in a PC has a direct affect on the system`s speed.
• The more RAM a PC has.the more program instructions and data can be held in memory,which is faster than storage on disk.
• If a PC does not have enough memory to run a program,it must move data between RAM and the hard disk frequently.This process called swapping,can greatly slow a PC`s performance. 

                                        More RAM=Better Performance!  

The System Clock: 

• The computer`s system clock sets the pace the CPU by using a vibrating quartz crystal.
• A single "tick" of the clock is the time required to turn a transistor off and back on.This is called a clock cycle.
• Clock cycles are measured in Hertz(Hz),a measure of cycles per second.If a computer has a clock speed of 300 MHz, then its system clock"ticks" 300 million times every seconds.
• The faster a PCs clock runs,the more instructions the PC can execute each second. 

The Bus: 

• A bus is a path between the components of a computer.Data and instructions travel along these paths.
• The data bus width determines how many bits can be transmitted between the CPU and other devices.
• The address buss runs only between the CPU and RAM, and carries nothing but memory addresses for the CPU to use.
• Peripheral devices are connected to the CPU by an expansion bus. 

Cache Memory: 

• Cache memory is high-speed memory that holds the most recent data and instructions that have been loaded by the CPU.
• Cache is located directly on the CPU or between the CPU and RAM,making it faster than normal RAM.
• CPU-resident cache is called Level-1 (L1)cache.External cache is called Level-2(L2) cache.
• The amount of cache memory has a tremendous impact on the computer`s speed.

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Extending The Processor`s Power To Other Devices

• Ports
• Expansion Slots and Boards

Ports: 

• External devices-such as those used for input and output-are connected to the system by ports on the back of the computer.
• PC`s feature a number of built-in ports,which are ready to accept devices such as printer,mouse,keyboard,phone line,microphone and speakers and others
• Most computers come with a serial port and a parallel port.A serial port transmits one bit of data at a time;a parallel port transmits data one byte at a time.

Expansion Slots and Boards: 

• If the PC does not have a port for an external device,we can install an expansion board into one of the empty expansion slots.
• A board provides the correct port for the new device, and connects the device to the CPU by way of the computers expansion bus.
• Newer bus technologies such as Universal Serial Bus(USB)and IEEE 1394 enable many devices to be connected to one port.
• Small computer system Interface(SCSI) is an older standard for extending the bus to multiple devices through a single port. 

How Computers Process Data

Where Processing Occurs:

• The Control Unit
• The Arithmetic Logic Unit
• Machine Cycles
• The Role of Memory in Processing 
• Types of RAM

Where Processing Occurs: 

• Processing takes place in the PC`s central processing unit(CPU).
• The system`s memory also plays a crucial role in processing data.
• Both the CPU and memory are attached to the system`s motherboard,which connects all the computers devices together,enabling them to communicate.

The Control Unit:The two main parts of a CPU are the control unit and the arithmetic logic unit(ALU).

• The control unit directs the flow of data through the CPU, and to and from other devices.
• The control unit stores the CPU`s microcode, which contains the instructions for all the tasks the CPU can perform.

The Arithmetic Logic Unit: 

• The actual manipulation of data takes place in the ALU.
• The ALU can perform arithmetic and logic operations.
• The ALU is connected to a set of resisters-small memory areas in the CPU, which hold data and program instructions while they are being processed.

Machine Cycles: 

• The CPU follows a set of steps-called cycle for each instruction it carries out.
• By using a technique called pipelining,many CPU`s can process more than one instruction at a time.
• During the instruction cycle,the CPU "fetches" a command or data from memory and "decodes" it for the CPU
• During the execution cycle,the CPU carries out the instruction, and may store the instruction`s result in memory.

The Role of Memory: 

• RAM stores data and program code needed by the CPU.The contents of RAM change rapidly and often.
• Read-only memory (ROM) is nonvolatile(or permanent).It holds instructions that run the computer when the power is first turned on.
• The CPU accesses each location in memory by using a unique number,called the memory address.

Types of RAM: 

There are two types of RAM:static and dynamic.

• Dynamic RAM (DRAM)chips must be recharged with electricity very frequently,or they will lose their contents.
• Static RAM  (SRAM) does not need to be recharged as often as DRAM, and can hold its contents longer.

Another type of RAM,called flash memory, can store its contents after power is turned off.Flash memory is used in digital cameras to store pictures.

PC Projector - A useful thing in our life

• A PC projector connects to a PC and is used to project images on a large screen.
• Many PC projectors provide the same resolutions and color levels as high-quality monitors.
• Digital light processing(DLP)projectors use a microchip containing tiny mirrors to produce very sharp,bright images. 

Introducing-Bar Code Readers

• Bar code reader can read bar codes-patterns of printed bars.
• The reader emits light,which reflects off the bar code and into a detector in the reader.The detector translates the code into numbers.
• Flatbed bar code reader are commonly found in supermarkets.Courier services often use handheld readers.

Alternative Input Devices

Devices for the Hand:

• Pens
• Touch Screens
• Game Controller

Pens: 

• With a pen-based system,we use an electronic pen to write on the screen and choose command.
• Pens are common input devices for  handheld computers,like"Personal digital assistants(PDAs)."
• Pens are handy for making notes or selecting commands,not for inputting a lot of text.

Touch Screens:

                                                            

• Touch-screen systems accept input directly through the monitor.
• Touch screens use sensors to detect the touch of a finger.They are useful where environmental conditions prohibit the use of a keyboard or mouse.
• Touch-screen system are useful for selecting options from menus. 

Game Controller: 

• The two primary types of game controllers are joysticks and pads.
• Game pads usually provide controls for each hand.
• joysticks are popular for flight simulator and driving games. 

                                        

How a Keyboard Works

When we press a key:

• The keyboard controller detects the keystroke.
• The controller places a scan code in the keyboard buffer, indicating which key was pressed.
• The keyboard sends the computer an interrupt request,telling the CPU to the keyboard.

Keyboard

Mouse Techniques

Using the mouse involves five techniques:

1. Pointing:Move the mouse to move the on-screen pointer.
2. Clicking:Press and release the left mouse button once.
3. Double-Clicking:Press and release the left mouse button twice.
4. Dragging:Hold down the left mouse button as you move the pointer.
5. Right-Clicking:Press and release the right mouse button.

Variants of the Mouse

• Trackballs
• Trackpads
• Integrated Pointed Devices         

Trackballs:

• A trackball is like a mouse turned upside-down.
• Use your thumb to move the exposed ball and your fingers to press the buttons.

Trackpads:

• A trackpad is a touch-sensitive pad that provides the same functionality as a mouse.
• To use a a trackpad, we glide our finger across its surface.
• Trackpads provide a set of buttons that function like mouse buttons.

Integrated Pointed Devices:

• An integrated pointing device is a small joystick built into the keyboard.
• To use an integrated pointing device,we move the joystick.
• These devices provide a set of buttons that function like mouse buttons.

                                                

Software: Bringing the Machine to Life

What is Software:

• Software is a set of electronic instructions that tells the computer how to do certain tasks.A set of instructions is often called a program.
• When a  computer is using  a particular program,it is said to be running or executing the program.
• The  two most common types of programs are system software and application software.  

System Software: 

• System software exists primarily for the computer itself,to help the computer perform specific function.
• One major type of system software is the operating system(OS).All computers require an operating system.
• The OS tells the computer how to interact with the user and its own devices
• Common operating systems include Windows,The Macintosh OS,OS/2,UNIX.   

Application Software:  

• Application software tells the computer how to accomplish tasks the user requires,such as creating a document or editing a graphic image.
• Some important kinds of application software are:

                    Word processing programs

                    Database management

                    Graphics programs

                    Browsers

                    Networking software

                    Internet applications

and so on..                

Types of Hardware

A computer hardware devices are categorized as follows:

• Processor
• Memory
• Input and Output(I/O)devices
• Storage devices

PROCESSOR: The procedure that transforms raw data into useful information is called processing.The processor is also called the central processing unit(CPU).It manage all devices and performs the actual processing of data.

The CPU consists of one or more chips attached to the computers main circuit board(the motherboard).

MEMORY:              

• Memory also consists of chips attached to the motherboard.
• Memory holds data and program instructions as the CPU works with them.This memory is called Random Access Memory(RAM).
• The CPU can find any piece of data in RAM,when it needs it for processing.
• RAM is volatile,meaning it holds data only when the power is on.When the power is off, RAMs contents are lost.

Input and Output devices: 

• Input devices accept data and instructions from the user or from another computer system.The keyboard and mouse are examples of input devices.
• Output devices return processed data back to the user or to another computer system.The printer and monitor are examples.
• Communications devices(such as modems and network interface cards) perform both input ant output,allowing computers to share information.           

 Storage devices:

• Storage devices hold data not currently being used by the CPU.Data is commonly stored on a magnetic or optical disk.Each type uses a special medium for storing data on its surface.
• A disk drive is a device that reads data from and writes data to a disk.Most new computers feature a floppy disk drive,a hard disk drive and an optical disk drive.
• The most common optical storage devices are CD-ROM and DVD-ROM drives.

How Memory is Measured

• The smallest usable unit of measure for memory is the byte-the amount of memory required to hold one character,like the letter A or the numeral 2.
• Computer work with largest chunks of data,measured in multiple bytes,as shown below;

UNIT                Approx. value(bytes)     Actual Value(bytes)      
kilobyte(KB)      1,000                               1,024

Megabyte(MB)   1,000,000                        1,048,576

Gigabyte(GB)     1,000,000,000                 1,073,741,824

Terabyte(TB)     1,000,000,000,000           1,099,511,627,776

The Parts of a Computer System

A computer is an electronic device used to process data.

• A computer can convert data into information that is useful to people.
• A complete computer system includes four distinct parts:

                      Hardware

                      Software

                      Data

                      User

Hardware:  

• A computers hardware consists of electronic devices; the parts we can see and touch.
• The term "device" refers to any piece of hardware used by the computer,such as a Keyboard,Monitor,Modem,Mouse etc.

Software: 

• Software-also called programs-consists of organized sets of instructions for controlling the computer.
•  Some programs exist for the computers use,to help it manage its own tasks and devices.
• Other programs exist for the user, and enable the computer to perform tasks for us.such as creating documents.

Data:   

• Data consists of raw facts,which the computer can manipulate and process into information that is useful to people.
• Computerized data is digital,meaning that it has been reduced to digits or numbers.The computer stores and reads all data as numbers.
• Although computers use data in digital form,they convert data into forms that people can understand.such as text,numerals,sounds,images etc.    

User:

• People are the computers operators or users.
• Some types of computers can operate without much intervention from people,but personal computers are designed specifically for use by people.

                                                                                                             

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