Computer Hardware and Software

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# Computer Hardware and Software - PowerPoint PPT Presentation

Computer Hardware and Software. Jinchang Wang. Hardware vs. Software. Hardware is something tangible. Computer hardware includes electronic circuitry and mechanisms. Software is instructions. Computer software is instructions to computer. Electronic Computer.

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Presentation Transcript

### Computer Hardware and Software

Jinchang Wang

Hardware vs. Software
• Hardware is something tangible.
• Computer hardware includes electronic circuitry and mechanisms.
• Software is instructions.
• Computer software is instructions to computer.
Electronic Computer
• In an electronic computer, main computing operations are accomplished on electronic switches at speed of electricity.
Binary Numbers
• A binary number is composed of 0’s and 1’s.
• Binary numbers and decimal numbers are two ways of recording numbers.
Only 0-1’s inside a Computer
• Everything (program, data, music, picture) in computer is coded in binary numbers that are composed of two digits, 0 and 1.
• Two distinctive, and reliable, states of an electronic circuit are off and on, corresponding to 0 and 1.
Bit and Byte
• One binary digit is called a bit.
• For example, binary number 1011 has four bits.
• 1 byte = 8 bits.
• A character (a, A, b, B, ..., \$, *, ...) is represented by a byte.
• 01100001 for 1
• 01011001 for Y
• 00110010 for 2
• 00111011 for ;
Storage Capacity Measures
• 1 Kbyte = 1 kilobyte  1,000 bytes
• 1 Mbyte = 1 megabyte  1,000,000 bytes
• 1 Gbyte = 1 gigabyte  1,000,000,000 bytes
• 1 Mbyte can store a novel with 500 pages (pure text)
Components of a Computer

Input devices

CPU

Internal memory

Secondary storage

Output devices

Input Devices
• To enter instructions and data into computers.
• Keyboard
• Mouse, trackball, joystick, …
• Pen-based input devices
• Scanners
• Voice input devices
CPU
• Central Process Unit
• CPU is composes of:
• Control Unit:
• Interprets programs (decoding)
• Directs and controls operations
• Arithmetic and Logic Unit
• Performs computations.
• Performs logical comparisons.
Microprocessor
• CPU on a chip
• A chip is a self-contained integrated circuit
Internal Memory
• Made up of electronic circuits.
• Data and instructions are stored in it before they are processed in CPU.
RAM and ROM
• RAM
• For users to store programs and data
• Volatile
• ROM
• For storing instructions for startup and common instructions
• Non-volatile
Secondary Storage
• Permanent storage – non-volatile
• Huge storage capacity
• Much slower than internal memory
• Hard disc, flash drive, optical disk, …
Hard Disk (1)
• Fixed magnetic disk
• 1 to 5.25 inches
• 20 GB to 200 GB
• Contains 12 disk platters stacked on a spindle
Output Devices
• Monitors
• CRT, LCD
• Printers
• Laser printers, Ink-jet printers
Computer Software
• Computer software refers to instructions to computer.
• A computer program is a set of instructions for some purpose.
An Example of a Program- You enter a name, computer tells his/her address

Print “Enter a name” on screen;

Let X=(name-entered);

flag=0;

i=1;

Do repeatedly until flag=1:

if name-stored(i) = X,

then

flag = 1;

otherwise

i=i+1;

Stop.

Types of Software
• System software – to control the hardware and basic operations of a computer
• Operating system
• Utility software – for basic operations but not covered by operating systems.
• Application software – for particular applications.
Operating System
• Control internal memory, input/output devices, and secondary memories.
• Support other software
• Every computer has an operating system