2. MEMORY STRUCTURE
Bit (Binary Digit) – A binary digit is logical 0 and 1
Nibble- A group of 4 bits
Byte – A group of 8 bits
Word - A group of fixed number of bits processed as a unit
- varies from computer to computer
By grouping bits together we can store more values
• 8 bits = 1 byte
• 16 bits = 2 bytes = 1 halfword
• 32 bits = 4 bytes = 1 word
4. NUMBER SYSTEM
Decimal (base-10) number system
• We have symbols (digits) that can represent ten integer values: 0, 1, 2, 3, 4, 5, 6, 7, 8,
9
• We represent integer values larger than 9 with combinations of two or more digits,
e.g.: 10, 11, 12, ..., 112, ..., 247
e.g.: 247
= (7 x 100 ) + (4 x 101 ) + (2 x 102 )
2 is the Most Significant Digit
7 is the Least Significant Digit
5. NUMBER SYSTEM
Binary (Base 2) Number system
• Computer systems store information electronically using bits (binary digits)
• Each bit can be in one of two states, which we can take to represent the binary (base-2)
digits 0 and 1
• The binary number system is a natural number system for computing (rather than the
decimal system)
• Using a single bit, we can represent integer values 0 and 1
• Using two bits, we can represent 0, 1, 10, 11
6. NUMBER CONVERSION
• Binary to Decimal Conversion
100101 = (1 x 20 ) +
(0 x 21 ) + LSB - Least Significant Bit
MSB LSB (1 x 22 ) + MSB – Most Significant Bit
(0 x 23 ) +
(0 x 24 ) +
(1 x 25 ) +
= 37 (100101)2 = (37)10
7. • Binary fraction to Decimal Conversion
NUMBER CONVERSION
11001.11
decimal part 11001= fractional part .11 =
( 1 x 20 ) = 1+ (1 x 2 -1 ) + = 0.50 +
( 0 x 21 ) = 0+ (1 x 2 -2 ) = 0.25
( 0 x 22 ) = 0 +
( 1x 23 ) = 8 + = .75
( 1 x 24 ) = 16
= 25
(11001.11)2 = (25.75)10