Definition of a Computer

• A computer is an device that receives information (input), processes information, and outputs information

• input/output device that processes information

Essential Parts

• Box - Central Processing Unit (CPU)

• Monitor - main output device

• Keyboard - main input device

• Mouse – optional input device

The Box (CPU)

• All processing goes through the box• A simple input/output (I/O) device• Ports on back for connection of input and output

devices• Disk drives on front for storage I/O• Processor – e.g. Pentium IV• Memory – e.g. 256 MB RAM• Storage – e.g. Hard Drive, CD-RW• Slots & Cards

Input Devices

• Human input devices– Allow person to send data to the computer– Keyboard– Mouse (and other pointing devices)

• Machine-readable input devices– Send data directly to computer without human

involvement– No human involvement means no human error– Usually faster than human input

Input Output Devices

Input Devices• Keyboard• Scanner• CD-ROMOutput Device• Digital Camera• LCD Projector• Laser Pointer• Speakers• Monitor• Printer

Machine Readable• CPU (The Box) • Hard Drive• Floppy Drive• Modem • CD Writer/Burner • Network Card • Bluetooth Card

Input: MiceInput: MiceStandard Two-Button: Left Standard Two-Button: Left button for selecting, right button button for selecting, right button for propertiesfor propertiesWheeled Mouse - Wheel for Wheeled Mouse - Wheel for scrollingscrollingTrackball - Inverted mouseTrackball - Inverted mouseTouchpad - Touch/tap sensitiveTouchpad - Touch/tap sensitive““Eraser”/JoystickEraser”/Joystick

Output: Types of Monitors

• Cathode Ray Tube (CRT) - standard monitor, inexpensive, good resolution, good pixel size

• Flat Panel (Liquid Crystal Display - LCD) – more expensive, prices dropping

Hard Disk Drives and Direct Access

Thank You

Unit Description Approximate Size

1 bit 1 binary digit

1 nibble 4 bits

1 byte 8 bits 1 character

1 kilobyte 1,024 bytes 1/2 page

1 megabyte 1,048,576 bytes 500,000 pages 1 million bytes

1 gigabyte 1,073,741,824 bytes 5 million pages 1 billion bytes

1 terabyte 1 trillion bytes 5 billion pages 2000 CD’s

1 Petabyte 1,125,899,906,842,624 Bytes 1,60,000 DVD’s

1 Exabyte 1,152,921,504,606,846,976 Bytes ½ the amount of data generated world wide in a year

1 Zettabyte 1,180,591,620,717,411,303,424 Bytes As much data as grains of sand on all the world beaches

Yottabyte 1,208,925,819,614,629,174,706,176 Bytes As much as the no of atoms in two table spoons of water