Computer fundamentals

Computer fundamentals Data Representation in Computers... Data Representation Data is stored in a computer in binary format as a series of 1s and 0s..  Computers use standardized codin

Computer

fundamentals

Data Representation in Computers

 Introduction (Bit, Byte, KB, MB, GB)

 The Decimal Number System

 The Binary Number System

 Number Conversion between Number Systems

 Data Storage

 Binary Arithmetic

 Unit of Information

Data Representation

 Data is stored in a computer in binary format as a

series of 1s and 0s

 Computers use standardized coding systems (such

as ASCII) to determine what character or number is represented by what series of binary digits

 Data is stored in a series of 8-bit combinations

called a byte

 Every letter, number, punctuation mark, or symbol

has its own unique combination of ones and zeros

Data Representation

On

Off

 A bit or binary digit has one

of two values, zero or one

 A byte is the smallest

addressable unit of memory

(8 bits)

 ASCII provides for 256

(or 28) characters

 01000001 – A

 01000010 – B

 etc

Memory Bits and Bytes

8 Bits = 1 Byte

Memory Bits and Bytes

 Bits are switches turned ‘on’ or ‘off’

 ON bits are said to be in a 1 state

 OFF bits are said to be in a 0 state

Memory Bits and Bytes

 ON bits are said to be in a 1 state

 OFF bits are said to be in a 0 state

Combination of 1’s and 0’s represent the letters, numbers, and special characters.

Bits and Bytes

 8 bits = 1 Byte (1 keyboard character)

 1,024 bytes = 1 Kilobyte (1K)

 1,024 K = 1 Megabyte (MB)

 1,024 MB = 1 Gigabyte (GB)

 Transient (erased when power turned off)

 Consider a UPS (uninterrupted power supply)

 Measured in bytes

 1 Kilobyte = 2 10 characters (~1,000 bytes)

 1 Megabyte = 2 20 characters (~1,000,000 bytes)

 1 Gigabyte = 2 30 characters (~1,000,000,000 bytes)

 Need 256Mb or 512Mb of RAM

 Keep multiple programs & data files in memory

 Graphic-intensive programs demand a lot of memory

 The Original PC had 16Kb of memory

The Decimal Number

System

 In the decimal system use from 0 to 9

 We consider the number: 365

(3x100) + (6x10) + (5x1) = 365

(3x102) + (6x101) + (5x100) = 365

 Thus as we move one position to the left, the value of the digit increases by ten times

 The value of each digit in the number system is

determined by:

- The digit itself

- The position of the digit in the number itself

The Binary Number System

 The binary number system has a base of two, and symbols used are 0 and 1.

 Example: 1010

(1x8) + (0x4) + (1x2) + (0x1) = 1010

(1x23) + (0x22) + (1x21) + (0x20) = 1010

 Thus as we move to the left the value of the digit will

be two times greater than its predeccessor

 The value of the places are:

Converting Binary to Decimal

 The decimal equivalent of 110100 is

(1x32) + (1x16) + (0x8) + (1x4) + (0x2) + (0x1)

= 32 + 16 + 0 + 4 + 0 + 0

= 52

Converting Decimal To

Binary

 In conversion from decimal to any other

number system, the steps to be followed are:

- Divide the decimal number by the base of the requred number system

- Note the remainder in one column and divide the qoutient again with the base Keep repeating

this process until the quotient is reduced to a zero

- Reading off the remainder in the reverse order

of them being written down will give us the required

Converting Decimal To Binar y

 Example: Convert the decimal number 52 to its binary equivalent

2 52

2 26

2 13

2 06

2 03

2 01

2 00

0 0 1 0 1 1

 Thus the binary equivalent of the decimal