A computer consists of a central processing unit (CPU) that processes information, and input/output devices like a keyboard, mouse and monitor to input and output information. The CPU contains the processor, memory and storage and has ports to connect input/output devices. Common input devices include keyboards for human input and storage drives for machine input. Output is mainly through monitors but also includes printers and speakers.

2. Definition of a Computer
• A computer is an device that receives
information (input), processes information,
and outputs information
• input/output device that processes
information

3. Essential Parts
• Box - Central Processing Unit (CPU)
• Monitor - main output device
• Keyboard - main input device
• Mouse – optional input device

4. 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

7. 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

8. Input Output
Devices
Input Devices Machine Readable
• Keyboard • CPU (The Box)
• Scanner • Hard Drive
• CD-ROM • Floppy Drive
Output Device • Modem
• Digital Camera • CD Writer/Burner
• LCD Projector • Network Card
• Laser Pointer • Bluetooth Card
• Speakers
• Monitor
• Printer

9. Input: Mice
Standard Two-Button: Left
button for selecting, right button
for properties
Wheeled Mouse - Wheel for
scrolling
Trackball - Inverted mouse
Touchpad - Touch/tap sensitive
“Eraser”/Joystick

11. 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

13. Hard Disk Drives and Direct
Access

14. Thank You

15. 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