Lecture # 2

Computer Hardware

Computers are all around!

• Grocery store• Schools• Libraries• Bank• Mail• Malls

We interact with computers everyday!We interact with computers everyday!

A computer is an electronic device, operating under the control of instructions (software) stored in its own memory unit, that can accept data (input), manipulate data (process), and produce information (output) from the processing. Generally, the term is used to describe a collection of devices that function together as a system.

Computer System

• A computer can convert data into information that is useful to people.

• A complete computer system includes four distinct parts:

Hardware

Software

Data

User

A computer is an electronic device used to process data.

Computer System

Understanding Computer

“A computer is a programmable machine

that receives input, stores and manipulates data/information, and provides output in a

useful format.”

• Hardware All the machinery

and equipment in a computer system

• Software All the instructions

that tell the computer how to perform a task

Computers consist of hardware and software.

If you can touch it, it’s hardware

Off and On

• Computers only recognize off and on, like a light switch

• These switches are represented as binary digits or… bits

• Instructions and data are composed only of a series of bits

Why Is A Computer So Powerful?

• The ability to perform the information processing cycle with amazing speed.

• Reliability (low failure rate).

• Accuracy.

• Ability to store huge amounts of data and information.

• Ability to communicate with other computers

How Does a Computer Know what to do?

• It must be given a detailed list of instructions, called a compute program, algorithms or software, that tells it exactly what to do.

• Before processing a specific job, the computer program corresponding to that job must be stored in memory.

• Once the program is stored in memory the computer can start the operation by executing the program instructions one after the other.

What Are The Primary Components Of A Computer ?

• Input devices.• Central Processing Unit (containing the control unit and the

arithmetic/logic unit).• Memory.• Output devices.• Storage devices.

Input Process Output

DataInformation

Storage

How a Computer System Works

Function of Computer System

Data handling

I Input

P Process

O Output

S Storage

0100101001101010

011011111000111110000000

Off and On

• Computers only recognize off and on, like a light switch

• These switches are represented as binary digits or… bits

• Instructions and data are composed only of a series of bits

• A binary digit (bit) is the smallest unit of information that your computer can process.

• A bit can be either 1 (on) or 0 (off).

• ASCII is a common coding system used to represent all characters, symbols and numbers in binary form.

• In ASCII a group of 8 bits is called a byte.

HARDWARE: Your Physical Interface

Example:– If you type cool on the keyboard, your keyboard

would change it into four bytes as follows:

01000011 01001111 01001111 01001100 C o o l

HARDWARE: Your Physical Interface

Bytes

• Eight bits form a single byte– “00110011” is One Byte of Information

• Byte Values:– 00000000 = 0– 11111111 = 255

• As a result, binary numbers almost always written as a full byte (00000001).

We count in Base 10 (Decimal)

01234567891011121314959697989910010115161718192021222324Ran out of symbols (0-9), so increment the digit on the left by one unit.

Computers count in Base 2 (Binary)

• Counting in Binary is the same, but with only two symbols– On (1)– Off (0)

0110111001011111000100110101011110011011110111110000110

Converting Binary to Decimal

1 0 1 0 1 1 0 0

1248163264128

00480320128

+ + + + + + +

128 + 32 + 8 + 4 = 172

Converting Binary to Decimal

0 1 0 1 0 0 0 1 124816326412

8

1000160640 + + + + + + +

64 + 16 + 1 = 81

Converting Binary to Decimal

- - - - 124816326412

8

124016000 + + + + + + +

16 + 4 + 2 + 1 = 23

Size Matters

Computer memory and storage capacities are represented by their size (megs, gigs, etc)– 1 , 0 = 1 bit– 4 bits = 1 hex character (nibble) – 8 bits = 1 byte – 2^10 = 1,024 bytes or 1 Kilobyte (thousand) – 2^20 = 1,048,576 bytes or 1 Megabyte (million) – 2^30 = 1,073,741,824 or 1 Gigabyte (billion) – 2^40 = 1,099,511,627,776 bytes or

1 Terabyte (trillion)

Generic Input devices

• Accept data or commands and convert them to electronic form

• Getting data into the computer– Typing on a keyboard

– Pointing with a mouse

– Scanning with a wand reader or bar-code reader

Keyboard

• Data is entered by manually typing certain keys.

• A keyboard typically has 101 or 105 keys.

• Most keyboards use the QWERTY layout, named for the first six keys in the top row of letters.

Generic Input Devices

Rollup Keyboards

gaming keyboard

Generic Input Devices

MOUSE• Is a pointing device which is

used to control the movement of a mouse pointer on the screen to make selections from the screen.

• The bottom of the mouse contains a mechanism that detects movement of the mouse.

Specialized Input Devices