Section1 General Concepts. What is a computer? A computer is a machine that processes data or information according to a step by step sequence of instructions.

Section1

General Concepts

What is a computer?• A computer is a machine that processes data

or information according to a step by step sequence of instructions

• A computer can do a variety of different tasks at a time. It is multitasking

• Can store data (storage)• Can execute a sequence of instructions.

Advantage of Computers :

1.Speed2.Accurate3.Save Data4.Save Time5.Network

Data and informationData is raw facts collected for

processing

Information : is the processed facts

Data Information

Processing

Types of computer According to their Size :

1.Supercomputers.2. Mainframe Computer.3. Minicomputers.4. Microcomputers.

1. Supercomputers : the most powerful type, special high capacity machine used for large organization

2.Mainframe Computer : occupy specially wired , air condition room not powerful as super computer but it is capable of great processing speed and data storage ex: insurance companies.

3.Minicomputers : also referred to as midrange or server less powerful than mainframe but more powerful than microcomputers , it used in large companies to support processing needs , retrieving data from databases

4.Microcomputers : least powerful but most widely used , fastest growing type of computer.

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Types of Microcomputer

1. Desktop Computer (Personal Computer PC)2. Notebook or laptop 3. Netbook4. Tablet PC 5. Handheld (PDA)

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Desktop Computers

It is Small enough to Fit on the top of analog side the desk , yet too big to carry

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Notebook or laptop computers

Notebook computers also known as laptop computers , are portable and lightweight and fit into most briefcase

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Netbook

Similar to Notebook computersbut smaller , lighter and less expensive

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Tablet PC

The newest type of computer , they are smaller , lighter , less powerful than notebook have flat touchscreen and virtual keyboard ex : Apple Ipad

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Handheld (PDA)

PDA ( Portable Digital Assistant) :Smallest type of computers , designed to fit in the one hand , some of combine pen input and writing recognition like smartphones

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Computer Components1.Hardware : Physical component, a part you can see and touch

2 .Software : The “programs” which a set of information that tell the computer what to do and how to do it

What is hardware?Physical component, a part you

can see and touchA hardware components :1. input device2. output device3. central processing Unit (CPU)4. storage device

What is a peripheral device?

Hardware connected to computer to extend or improve its functionality .example: printer, scanner, flash drives, DVD ,camera, speakers, microphones

1. The Input Units

Input Units : are the units which translate the data from users to processing units

Any machine that feeds data into a computer.Some hardware input devices include

Barcode Keyboard

Joystick Mouse

Digital Camera Scanner

Keyboard : is board containing the keys of letters , numbers and some functionjoystick:

A joystick is an input device commonly used to control video gamesScanner : is an electronic device that generates a digital representation of an image for data input to a computerBar Code Reader : photoelectric scanner that translate the bar code symbols into digital form

Digital Camera :Images recorded digitally on disk or in camera’s memory Web Cam:Specialized digital video cameras built-in or attached to the monitor

Microphone:Used to enter and record voices to the computer

Mouse : a small device, which you move across the top of the desk to move the pointer or cursor on the screen , can use rolling ball or laser

Trackball:A trackball is an input device used to enter motion data into computers or other electronic devices. It serves the same purpose as a mouse, but is designed with a moveable ball on the top, which can be rolled in any direction. Instead of moving the whole device

.

Touchpad:A touch pad is a device for pointing (controlling input positioning) on a computer display screen. It is an alternative to the mouse. Originally incorporated in laptop computers, touch pads are also being made for use with desktop computers. A touch pad works by sensing the user's finger movement and downward pressure.

computer stylus/pens:an input device used to write text or draw lines

on a surface as input to a computer.

2.The Output Units

Output units : are the units which translate the processing units to users

Monitor

Printer

Speakers

Monitor : like T.V screen used to show pictures and texts

Speakers : it convert the voice analog to heard by the user

Printer : used to make a paper copy of the information into the computer.

Plotter: A graphics printer that draws images with ink pens. It actually draws point-to-point lines directly from vector graphics files.

Output Devices Input Devices

1. Computer monitor

2. Flat screen3. Projector4. Speakers and

headphones5. Printers

1. Keyboard2. Mouse3. Scanners4. Joysticks5. Web cams6. Digital cameras7. Microphones

Devices used for input and output processes

Touch screen

Fax Machine

Modem

3. CPU Central Process Unit (CPU): consider Brain of the computer

It contain two units :1. Arithmetic-Logic Unit (ALU) : it performs the

mathematical and logical operations2. Control Unit (CU) : it directs the electronic signals

between memory and arithmetic logic unit

Some computers can have several CPUs running in parallel (EX: Mainframe computers )

3 .Memory Units

ROM RAM

Read Only Memory -Information stored by

the manufacturer -Non-volatile and

cannot be changed -CPU can read, data

and programs in ROM but the computer cannot change ROM

Random Access Memory

-Hold programs and data that are currently being accessed

- Data and programs stored in RAM are volatile (the information is lost when you switch off the computer)

4.Storage devices:A computer storage device is any type of hardware that stores data.

Drive type Capacity Speed

Hard drive High , big storage ,

hundreds (100) of gigabytes

Faster than CD, DVD, or floppy

DVD drive Capacity of 4 gigabytes

Slower than a hard disk drive

CD drive 650 megabytes Slower than a hard disk drive

Floppy drive Very low storage capacity

Slower than a hard disk drive

1.Hard disc drive:The hard disk drive is the main, and usually largest, data storage device in a computer. The operating system, software titles and most other files are stored in the hard disk drive.

2. Floppy disk:is a hardware device that reads data storage information. first types of hardware storage that could read/write a portable device. FDDs are used for reading and writing on removable floppy discs. Floppy disks are now outdated, and have been replaced by other storage devices such as USB.

3.USB flash drive:a small external flash drive that can be used with any computer that has a USB port.

4.Zip Drives:Can be described as a kind of improved version of a floppy disk.Zip drives have more data storage capacity than traditional floppy drives (100-750) megabytes.

5.Data Cartridges and Tape Drives:Tape drives are mechanisms that are in many ways like a traditional tape recorder or video cassette recorder.Used in companies and universities for backup and archive data for a long period

Measuring Memory: Size Data Measurement

Single Binary Digit (1 or 0) Bit

8 bits Byte

1,024 Bytes Kilobyte (KB)

1,024 Kilobytes Megabyte (MB)

1,024 Megabytes Gigabyte (GB)

1,024 Gigabytes Terabyte (TB)

Power supply and Fans• Computers require Direct Current (DC) • DC power provided by converting

Alternating Current (AC) from wall outlets or batteries

• Desktop computers use Power Supply Units

• Notebooks and handhelds use AC Adapters

Hardware Port Port is used to connect the

computer with a peripheral devices (input or output devices)

Common Ports : Port Name Usage Image

LPT ( Parallel Port)

used to connect printers and scanners

Serial Port used to connect external modem and mouse

USB Port used to connect a wide variety of devices like camera , flash driver , mice , keyboard ,printer

and more

PS/2 Port connect mouse or keyboard

video port connect a computer screen ( monitor)

Fire wire Port connect digital video camera and external hard drive

Ethernet (Network Port)

connect Network Cables into this port

The Computer performance Factors

1. Speed2. Storage

CPU Clock Speed : (Processing speed ) The number of times the CPU fetches and processes data or

instructions in a second .

The clock speed is given in Hertz (Hz). 1 MHz means that the device will run at one million cycles

per second,(1 MHz = 1000000 Hz)

1 GHz is a thousand million times, so that (1 GHz = 1000000000 Hz).

The more memory you have the faster the PC will appear to operate.

Other factors Bus Speed, cache memory , CPU cache capacity , hard disk rotation speed , video card also affects on the computer performance