1.
Course : AIT 204
Course Title : Computer Organization and Architecture (COA)
Course Credits : 3 + 0
Course Teacher : Dr. Y R Ghodasara & Prof. K. C. Kamani
College of Agricultural Information Technology
Anand Agricultural University
Anand
Unit I

2.
Explain Booting Process of a Computer
Step 1 : Power On
Step 2 : SMPS(Switch Mode Power Supply) will convert AC current to DC current and
split current to different voltage levels. This will give current to all components
of the motherboard.
Step 3 : BIOS Chip(Basic Input Output System) gets the control and POST
(Pre Operation Self Test) routines are executed to check your hardware.
Step 4 : If POST routines are executed successfully, BIOS will read first sector of the
hard disk. This sector is called MBR(Master Boot Record) sector.(512 bytes)
Step 5 : The instructions in MBR sector are executed and operating system is loaded
in memory.
Step 6 : Computer is booted.

3.
Digital
The word digital implies that the information is represented by variables that take limited number of discrete
states.
Definitions
Analog
The word analog implies that the information is represented by variables that take many discrete states.
Hardware
The hardware of computer consist of all the electronic components and electro mechanical devices present
in the computer.
Example : CD Drive, Hard disk, RAM, Processor
Software
The computer software consist of instructions and data that the computer manipulates to perform data
processing.
Example : Operating systems, compilers, Word, Excel, Power point
Firmware
In an electronic component, software is permanently written in hardware. This type of electronic component
is called firmware.
Example : BIOS Chip, Washing Machine Chip, Set top Box Chip
Program
A sequence of instructions for the computer is known as program.

4.
Computer Architecture
Computer architecture deals with the structure and behaviour of various functional mode use of the
computer.
Computer Organization
Computer organization deals with the way hardware components are connect together to form a computer
system.
Computer Design
Computer design deals with the development of hardware for the computer according to the given set of
specifications.

5.
Block Diagram of a Digital Computer
The hardware of a computer is divided into three major parts.
1. CPU (Central Processing Unit)
2. RAM (Random Access Memory)
3. IOP (Input Output Processor)
RAM
CPU
IOP Output DeviceInput Device

6.
CPU
The central processing unit contains an arithmetic and logical unit which manipulates data, number of
registers to store data and control circuits for fetching and executing instructions.
RAM
The memory of a computer contains storage for instructions and data. It is called random access memory
because the processor can access any location in memory at random and retrieve binary information with in
a fixed interval of time.
IOP
The input output processor contains electronic circuits for communicating and controlling the transfer of
information between the computer and outside world. The input output devices connected to the computer
are keyboard, mouse, printer, monitor, disk drive etc.

7.
Number Systems
Following number systems are used in the computer.
Binary System
Binary system contains two symbols.
0,1
Octal System
Octal system contains eight symbols.
0,1,2,3,4,5,6,7
Decimal System
Decimal system contains ten symbols.
0,1,2,3,4,5,6,7,8,9
Hexa Decimal System
Hexa decimal system contains sixteen symbols.
0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F

8.
Number System Conversion
Binary Octal Decimal Hexa Decimal
0000 1111
77
100
AF
0000 0011 1111 1010
1270
512
10F

9.
Representation of Information
Alpha Numeric Information
The alpha numeric information like name of the student, college name etc. represented by string of
characters. This information is represented by ASCII or EASCII or UNICODE character set format.
ASCII
The full form of ASCII is American Standard Code for Information Interchange.
ASCII is a seven bit binary representation.
It can represent 128 different symbols.
EASCII
The full form of EASCII is Extended American Standard Code for Information Interchange.
EASCII is a eight bit binary representation.
It can represent 256 different symbols.
UNICODE
The ASCII and EASCII character set can represent only upper and lower case alphabet.
Other languages characters are necessary to develop multilingual systems.
Unicode character set represents character from different languages like Japanese, Korean, South Asian
languages.
Unicode character set is a 16-bit representation of the symbol.

10.
Unsigned Integer Representation
Unsigned Integer Numbers are the numbers with positive sign.
Unsigned Integer Numbers are represented using unsigned integer representation scheme.
Examples :
Unsigned Integer 16-bit Representation
0 0000 0000 0000 0000
1 0000 0000 0000 0001
64 0000 0000 0100 0000
513 0000 0010 0000 0001
1024 ?
1023 ?
511 ?

11.
Signed Integer Representation
Signed Integer Numbers are the numbers with positive and negative sign.
Signed Integer Numbers are represented using 2’s complement representation scheme.
Examples :
1. How integer 10 is represented in 16-bit 2’s complement scheme ?
Step 1 : Make binary of 10 0000 0000 0000 1010
2. How integer -10 is represented in 16-bit 2’s complement scheme ?
Step 1 : Make binary of 10 0000 0000 0000 1010
Step 2 : Make Complement 1111 1111 1111 0101
Step 3 : Add binary 1 + 1
--------------------------------
Step 4 : Make Sum 1111 1111 1111 0110
3. How integer -1 is represented in 16-bit 2’s complement scheme ?
4. How integer -512 is represented in 16-bit 2’s complement scheme ?

12.
Floating Point Representation
The IEEE 754 standard is use to represent real numbers on the majority of computer systems.
It uses 32-bit pattern to represent single precision numbers and 64-bit pattern to represent double precision
numbers.
Single Precision (32-bit) Representation
Double Precision (64-bit) Representation
Equation 1 : ± 1.F X 2E-127 32-bit representation
Equation 2 : ± 1.F X 2E-1023 64-bit representation
In both cases, F is preceded with an implied one numeric and of binary point.
If sign bit value is 0 then number is positive and if value is 1 then number is negative.
Sign bit
1 – bit
Exponent E
8-bit
Fraction F
23-bit
Sign bit
1 – bit
Exponent E
11-bit
Fraction F
52-bit

13.
Example 1 : Store 5.5 in 32-bit format
Step 1 : 5.5
Step 2 : Make binary representation
101.1
Step 3 : Normalize binary representation
1.011 X 22 (± 1.F X 2E-127)
Step 4 : Get Exponent
E-127=2
E=129
Step 5 : Convert exponent in 8-bit binary
1000 0001
Step 6 : Number is positive, sign bit is zero.
Step 7 : Convert fractional part in 23-bit binary.
0110 0000 0000 0000 0000 000
Step 8 : Put sign bit, exponent and fractional part.
0 1000 0001 0110 0000 0000 0000 0000 000

14.
Example 2 : Convert 0100 0000 1011 0000 0000 0000 0000 0000
Step 1 : 0100 0000 1011 0000 0000 0000 0000 0000
Step 2 : Place sign bit, exponent and fractional part
100 0000 1
sign exponent fractional part
Step 3 : Sign bit is zero, number is positive.
Step 4 : E=1000 0001
E=129
Step 5 : Put values in formula.
± 1. 011 0000 0000 0000 0000 0000 X 2(129-127)
Step 6 : Number is positive, sign bit is zero.
Step 7 : Simplify and discard extra zero.
= ± 1.011 X 22
= 101.1
= 5.5
0 1000 0001 011 0000 0000 0000 0000 0000

15.
Example 3 : Store 15.5 in 64-bit format
Step 1 : 15.5
Step 2 : Make binary representation
1111.1
Step 3 : Normalize binary representation
1.1111 X 23 (± 1.F X 2E-1023)
Step 4 : Get Exponent
E-1023=3
E=1026
Step 5 : Convert exponent in 11-bit binary
100 0000 0010
Step 6 : Number is positive, sign bit is zero.
Step 7 : Convert fractional part in 52-bit binary.
1111 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
Step 8 : Put sign bit, exponent and fractional part.
0 100 0000 0010 1111 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000

16.
Example 4 : Store -11.75 in 32-bit format
Do it yourself.

17.
Logic Gates
Logic gate is a digital circuit created using transistors.
Using logic gate more complex digital circuits like register, memory, processor etc.
are created.
1. NOT Gate
This gate is also known as inverter.
It changes logic 1 input to logic 0 or changes logic 0 to logic 1.
A X
Logic NOT
A X
1 0
0 1
Truth Table
X = A’
OR
X = Ā
Boolean Function

18.
2. AND Gate
The operation of the AND gate is such that its output is logic 1 only if all of its inputs are logic 1 otherwise
the output is logic 0.
A B X
0 0 0
0 1 0
1 0 0
1 1 1
Truth Table
X = AB
OR
X = A.B
Boolean Function
A
X
Logic AND
B

19.
3. OR Gate
The operation of the OR gate is such that its output is logic 1 if any one input is logic 1 otherwise
the output is logic 0.
A B X
0 0 0
0 1 1
1 0 1
1 1 1
Truth Table
X = A+B
Boolean Function
A
X
Logic OR
B

20.
4. Exclusive OR Gate(XOR Gate)
The exclusive OR gate is sometimes called parity checker.
The exclusive OR gate counts the number of 1s at its input and give output logic 1 for an odd count and
logic 0 for even count.
A B X
0 0 0
0 1 1
1 0 1
1 1 0
Truth Table
X = A + B
Boolean Function
A
X
Exclusive OR Gate
B

21.
5. NAND Gate
The operation of the NAND gate is complement of AND gate.
A B X
0 0 1
0 1 1
1 0 1
1 1 0
Truth Table
X = (AB)’
OR
X = A.B
Boolean Function
A
X
Logic NAND Gate
B

22.
6. NOR Gate
The operation of the NOR gate function is complement of OR gate.
A B X
0 0 1
0 1 0
1 0 0
1 1 0
Truth Table
X = (A+B)’
OR
X = A + B
Boolean Function
A
X
Logic NOR Gate
B

23.
7. Exclusive NOR Gate(NOR Gate)
The exclusive NOR gate is complement of exclusive OR gate.
A B X
0 0 1
0 1 0
1 0 0
1 1 1
Truth Table
X = A + B
Boolean Function
A
X
Exclusive NOR Gate
B

24.
Definitions
Boolean Algebra
Boolean algebra is an algebra that deals with binary variables and logic operations.
Boolean Function
Boolean function can be expressed algebraically with binary variables, logic operation symbols,
parenthesis and equal sign. For a given values of variables, boolean function can be either 1 or 0.
Example : F = X + Y’Z
Truth Table
Truth table is a tabular representation of boolean function with different variable values.
Y Y’Z
Z
Y’
X
F
X Y Z Y’ Y’Z F=X+Y’Z
0 0 0 1 0 0
0 0 1 1 1 1
0 1 0 0 0 0
0 1 1 0 0 0
1 0 0 1 0 1
1 0 1 1 1 1
1 1 0 0 0 1
1 1 1 0 0 1

25.
Draw digital circuit using following boolean function.
F= A + B’C’
B B’C’
C
A
C’
B’
F = A + B’C’
INPUT OUTPUT
A B C B’ C’ B’C’ F=A+B’C’
0 0 0 1 1 1 1
0 0 1 1 0 0 0
0 1 0 0 1 0 0
0 1 1 0 0 0 0
1 0 0 1 1 1 1
1 0 1 1 0 0 1
1 1 0 0 1 0 1
1 1 1 0 0 0 1

26.
Draw digital circuit using following boolean function.
F= AB + A’C
ABA
F = AB + A’C
INPUT OUTPUT
A B C AB A’ A’C F=AB+A’C
0 0 0 0 1 0 0
0 0 1 0 1 1 1
0 1 0 0 1 0 0
0 1 1 0 1 1 1
1 0 0 0 0 0 0
1 0 1 0 0 0 0
1 1 0 1 0 0 1
1 1 1 1 0 0 1
B
C
A’
A’C

27.
Rules for Boolean Algebra
1. A + 0 = A
2. A . 0 = 0
3. A + 1 = 1
4. A . 1 = A
5. A + A = A
6. A . A = A
7. A + A’ = 1
8. A + B = B + A
9. A . A’ = 0
10. AB = BA
11. A + (B + C) = (A + B) + C
12. A.(BC) = (AB).C
13. A . (B+C) = AB + AC
14. A + BC =(A+B).(A+C)
15. (A+B)’ = A’B’
16. (AB)’ = A’ + B’
17. (A’)’ = A

28.
Circuit Simplification Using Boolean Algebra Rules
Example 1 Boolean Function F=ABC + ABC’ + A’C
ABCA
F = ABC + ABC’ + A’C
B
C
ABC’
A’C
INPUT OUTPUT
A B C ABC C’ ABC’ A’ A’C F=ABC+ABC’+A’C
0 0 0 0 1 0 1 0 0
0 0 1 0 0 0 1 1 1
0 1 0 0 1 0 1 0 0
0 1 1 0 0 0 1 1 1
1 0 0 0 1 0 0 0 0
1 0 1 0 0 0 0 0 0
1 1 0 0 1 1 0 0 1
1 1 1 1 0 0 0 0 1

29.
Circuit Simplification
F = ABC + ABC’ + A’C
= AB [ C + C’ ] + A’C
= AB.1 + A’C C+C’=1
= AB + A’C AB.1=AB
B
A
C
AB
A’C
F=AB+A’C
INPUT OUTPUT
A B C AB A’ A’C F=AB+A’C
0 0 0 0 1 0 0
0 0 1 0 1 1 1
0 1 0 0 1 0 0
0 1 1 0 1 1 1
1 0 0 0 0 0 0
1 0 1 0 0 0 0
1 1 0 1 0 0 1
1 1 1 1 0 0 1

30.
Circuit Simplification Using Karnaugh Map
Example 1 Boolean Function F=ABC + ABC’ + A’C
ABCA
F = ABC + ABC’ + A’C
B
C
ABC’
A’C
INPUT OUTPUT
A B C ABC C’ ABC’ A’ A’C F=ABC+ABC’+A’C
0 0 0 0 1 0 1 0 0
0 0 1 0 0 0 1 1 1
0 1 0 0 1 0 1 0 0
0 1 1 0 0 0 1 1 1
1 0 0 0 1 0 0 0 0
1 0 1 0 0 0 0 0 0
1 1 0 0 1 1 0 0 1
1 1 1 1 0 0 0 0 1

31.
0 1
0 1
1 1
0 0
Step 1 : Place Input-Output values in table
AB
C
00
01
11
10
0 1
Rectangle 1
A B C
0 0 1
0 1 1
Product of Rectangle 1 : A’C
Because A and C are constant
A’ because value of A is zero.
C because value of C is one.
Rectangle 2
A B C
1 1 0
1 1 1
Product of Rectangle 2: AB
Because A and Bare constant
A because value of A is one.
B because value of B is one.
Simplified Circuit using K-map = Rectangle 1 + Rectangle 2
= A’C + AB

32.
Exercise Boolean Function F=A’B’C’ + A’B’C + AB’C’ + ABC’
1. Simplify circuit using boolean rules.
2. Simplify circuit using Karnaugh Map.

33.
Concept of Machine Level, Assembly Level and High Level Programming
Processor
Assembler
Machine Level Language
Assembly Level Language
High Level Language
Compiler

34.
Machine Level Language
Machine level language is a language for processor.
Machine language is represented in binary code.
Machine level language is processor specific.
Assembly Level Language
It is hard to program in machine language.
To solve this problem, assembly language is used.
In assembly language, machine code is represented by Mnemonic code.
Assembly language is processor specific.
Assembler is a software to convert assembly language program in machine language.
High Level Language
It is hard to develop and maintain large application programs in assembly language.
To solve this problem, higher level languages like C,C++ etc. are used.
In assembly language, machine code is represented by Mnemonic code.
Compiler is a software to convert high level program to machine language.