1. Representing Data, Pictures, Time, and Size in Computer

2. Rationale
Today’s computers are based on integrated circuits (chips), each of which includes millions of subminiature transistors that are interconnected on a small (less than 1-inch-square) chip area.
Each transistor can be in either an “on” or an “off” position.

4. BITs
The “on-off” states of the transistors are used to establish a binary 1 or 0 for storing one binary digit, or bit.

5. BYTE
A sufficient number of bits to represent specific characters —letters, numbers, and special symbols—is known as a byte, usually 8 bits.
Because a bit has only two states, 0 or 1, the bits comprising a byte can represent any of 28, or 256, unique characters.
Which character is represented depends upon the bit combination or coding scheme used.

6. NIBBLE
A unit of four bits, or half an octet, is often called a nibble (or nybble). It can encode 16 different values, such as the numbers 0 to 15

7. CODING SCHEMES
ASCII (American National Standard Code for Information Interchange) - has emerged as the standard coding scheme for microcomputers
EBCDIC (Extended Binary Coded Decimal Interchange Code) - developed by IBM and is used primarily on large, mainframe computers

8. Representing Pictures
Pictures are represented by a grid overlay of the picture.
The computer measures the color (or light level) of each cell of the grid. The unit measurement of this is called a pixel.

9. Representing Time and Size of Bytes
Time is represented in fractions of a second.
Millisecond = 1/1000 second
Microsecond = 1/1,000,000 second
Nanosecond = 1/1,000,000,000 second
Picosecond = 1/1,000,000,000,000 second

10. COMPUTER SIZE Kilobyte = 1,000 bytes (actually 1,024)
Megabyte = 1,000 kilobytes = 106 bytes
Gigabyte = 109 bytes
Terabyte = 1012 bytes
Petabyte = 1015 bytes
Exabyte = 1018 bytes
Zettbyte = 1021 bytes
Yottabyte = 1024 bytes

11. NUMBER SYSTEM

12. CATEGORIES of NUMBER SYSTEM
Decimal – 10 digits; 0 to 9
Binary – 2 digits; 0 to 1
Octal – 8 digits; 0 to 7
Hexadecimal – 16 digits; 0 to 9, A to F

13. Hexadecimal to Decimal
CONVERSION
Binary to Decimal
Octal to Decimal
Hexadecimal to Decimal

14. How to convert binary numbers to decimal numbers?
10110
Working from right to left, MULTIPLY each position with 2 raised to the power of 0, 1,2, and so on… 20 21 22 23 24 1 2 4 8 16
Which is equal to
Add all of these and you will get 22. Hence, = 2210
Multiplied to each digit becomes

15. How to convert octal numbers to decimal numbers?
1037
Working from right to left, MULTIPLY each position with 8 raised to the power of 0, 1,2, and so on… 80 81 82 83 1 8 64
512 7 24
Which is equal to
Add all of these and you will get Hence, = 54310
Multiplied to each digit becomes