This document provides definitions and explanations of key concepts related to computers and programming. It defines what a computer is, computer programs, computer systems, software, hardware, operating systems, input/output devices, the CPU, storage devices, volatile and non-volatile memory, the program development life cycle, and the compilation process.

1. LOGIC BUILDING
TECHNIQUES

2. WHAT IS COMPUTER ?
A computer is a programmable machine or device that performs pre-defined or programmed computations
or controls operations that are expressible in numerical or logical terms at high speed and with great
accuracy.
Or
A computer is a digital electronics machine that can be programmed to carry out sequences of arithmetic or
logical operation automatically.
Or
Programmable machine designed to perform arithmetic and logical operation automatically and sequentially
as inputs given by users .

3. WHAT IS COMPUTER PROGRAM?
• A computer program is a sequence or set of instruction in a programming language for a computer to
execute. Computer programs are one component of software which also include documentation and
other intangible components.
WHAT IS COMPUTER SYSTEM?
• Computer System= Hardware + Software + User
• Computer system is made up of three main components :
a. Hardware = Internal devices + Peripheral devices : All physical part of the computer (or everything we
can touch) are known as hardware.
b. Software = Programs : Software gives “intelligence” to the computer.
c. User : Person who operate computer

4. WHAT IS SOFTWARE?
• Software is a set of instructions, data or programs used to operate computers and execute specific tasks.
For example, MS PAINT, ORACLE, JAVA, WINDOWS OPERATING SYSTEM etc. Software is
computer instructions that tell the hardware what to do. Software is programs, which are instruction sets
written by programmers.
• Types of Software:
a. Application Software: - Application software directs the computer to execute commands given by the
user and may be said to include any program that processes data for a user. For example, word
processors, spreadsheets, database management, inventory and payroll programs etc.
b. System Software: - System software is a type of computer program that is designed to run a computer’s
hardware and application programs. System software comprises the programs that you use to manage
your computer, including operating systems such as Windows, Linux, or UNIX for larger computers and
Google Android and Apple iOS for smartphones.

5. WHAT IS HARDWARE?
• Hardware is the equipment, or the physical devices, associated with a computer. For example,
keyboards, mice, speakers, and printers are all hardware. Hardware is the physical parts of a computer,
such as the processor, memory modules and the screen.

6. WHAT IS OPERATING SYSTEM?
• An operating system (OS) is system software that manages computer hardware and software resources
and provides common services for computer programs. The Operating System is often described as a
translator; it translates the language of the hardware (binary numbers) into the language of the software
(written programs) and then displays it in a way that humans can understand (text, images and sound).

7. WHAT IS INPUT DEVICES?
• An input device is a piece of hardware used to provide data to a computer used for interaction and
control. It allows the input of raw data to the computer for processing. Inputs are any devices that send
information into the computer. For example, a mouse has a position on the screen and is able to tell the
computer when a button is clicked and which button is clicked. A keyboard is able to send key presses to
the computer.

8. WHAT IS OUTPUT DEVICES?
• Outputs are any devices that are able to show information to the user. Good examples of these are the
screen, which shows the user text and images, and headphones, which are able to play sounds for the
user to listen to.

9. WHAT IS CPU?
• A Central Processing Unit is also called a processor, central processor, or microprocessor. It carries
out all the important functions of a computer. It receives instructions from both the hardware and active
software and produces output accordingly. It stores all important programs like operating systems and
application software. CPU also helps Input and output devices to communicate with each other. Owing
to these features of CPU, it is often referred to as the brain of the computer.
• The main processing device in any computer is the CPU (Central Processing Unit), which performs
binary calculations to make the computer run. This component is often referred to as the ‘brain of the
computer’.

10. • Generally, a CPU has three components:
a. ALU (Arithmetic Logic Unit) : It is the arithmetic logic unit, which performs arithmetic and logical
functions. Arithmetic functions include addition, subtraction, multiplication division, and comparisons.
Logical functions mainly include selecting, comparing, and merging the data.
b. Control Unit : The control unit (CU) is a component of a computer's central processing unit (CPU) that
directs the operation of the processor. It tells the computer's memory, arithmetic/logic unit and input and
output devices how to respond to the instructions that have been sent to the processor.
c. Memory or Storage Unit : It is called Random access memory (RAM). It temporarily stores data,
programs, and intermediate and final results of processing. So, it acts as a temporary storage area that
holds the data temporarily, which is used to run the computer.

11. WHAT IS STORAGE DEVICES?
• A storage device is any type of computing hardware that is used for storing, porting or extracting data
files and objects. Storage devices can hold and store information both temporarily and permanently.
They may be internal or external to a computer, server or computing device.

12. STORAGE UNIT

13. S. No. Volatile Memory Non-Volatile Memory
1.
Volatile memory is the type of memory in which data
is lost as it is powered-off.
Non-volatile memory is the type of memory in which data
remains stored even if it is powered-off.
2. Contents of Volatile memory are stored temporarily.
Contents of Non-volatile memory are stored
permanently.
3. It is faster than non-volatile memory. It is slower than volatile memory.
4.
RAM(Random Access Memory) is an example of
volatile memory.
ROM(Read Only Memory) is an example of non-volatile
memory.
5.
In volatile memory, data can be easily transferred in
comparison to non-volatile memory.
In non-volatile memory, data can not be easily
transferred in comparison to volatile memory.
6. In Volatile memory, process can read and write. In Non-volatile memory, process can only read.
7. Volatile memory generally has less storage capacity.
Non-volatile memory generally has more storage
capacity than volatile memory.
DIFFERENCE BETWEEN VOLATILE & NON-VOLATILE MEMORY

14. 8.
In volatile memory, the program’s data are stored
which are currently in process by the CPU.
In non-volatile memory, any kind of data which has to be
saved permanently are stored.
9. Volatile memory is more costly per unit size. Non-volatile memory is less costly per unit size.
10.
Volatile memory has a huge impact on the system’s
performance.
Non-volatile memory has a huge impact on a system’s
storage capacity.
11.
In volatile memory, processor has direct access to
data.
In non-volatile memory, processor has no direct access
to data.
12.
Volatile memory chips are generally kept on the
memory slot.
Non-volatile memory chips are embedded on the
motherboard.
13.
Advantages-
•Fast speed
•Low power consumption
•Better system performance as it increases speed
Advantages-
•More reliable
•Stores data permanently
•Inexpensive memory
•Helps in booting of operating system
14.
Disadvantages-
•Expensive
•Limited storage space
•Stores data temporarily
Disadvantages-
•Slow speed
•Can only read data

15. WHAT IS PROGRAM DEVELOPMENT LIFE CYCLE?
• Program development is the process of creating application programs. Program development life
cycle (PDLC) contains five phases of program development: analyzing, designing, coding, debugging
and testing, and implementing and maintaining application software.

16. • The following are six steps in the Program Development Life Cycle:
1. Analyze the problem. The computer user must figure out the problem, then decide how to resolve the
problem - choose a program.
2. Design the program. A flow chart is important to use during this step of the PDLC. This is a visual
diagram of the flow containing the program. This step will help you break down the problem.
3. Code the program. This is using the language of programming to write the lines of code. The code is
called the listing or the source code. The computer user will run an object code for this step.
4. Debug the program. The computer user must debug. This is the process of finding the "bugs" on the
computer. The bugs are important to find because this is known as errors in a program.
5. Formalize the solution. One must run the program to make sure there are no syntax and logic errors.
Syntax are grammatical errors and logic errors are incorrect results.
6. Document and maintain the program. This step is the final step of gathering everything together.
Internal documentation is involved in this step because it explains the reasoning one might of made a
change in the program or how to write a program.

17. WHAT IS COMPILATION PROCESS?
• After a computer program is typed using programming language statements and stored in memory, it
must be translated to machine language that represents the millions of on/off circuits within the
computer.
• Your programming language statements are called source code, and the translated machine language
statements are object code.
• Each programming language uses a piece of software, called a compiler or an interpreter, to translate
your source code into machine language.
• Machine language is also called binary language, and is represented as a series of 0s and 1s.
• After a program’s source code is successfully translated to machine language, the computer can carry
out the program instructions. When instructions are carried out, a program runs, or executes. In a typical
program, some input will be accepted, some processing will occur, and results will be output

18. WHAT IS COMPILATION PROCESS IN C LANGUAGE?
• The compilation is a process of converting the source code into object code.
• It is done with the help of the compiler. The compiler checks the source code for the syntactical or
structural errors, and if the source code is error free, then it generates the object code.
• The c compilation process converts the source code taken as input into the object code or machine code.
The compilation process can be divided into four steps, i.e., Pre-processing, Compiling, Assembling,
and Linking.

19. 1. Preprocessor : The source code is the code which is written in a text editor and the source code file is given an
extension ".c". This source code is first passed to the preprocessor, and then the preprocessor expands this
code. After expanding the code, the expanded code is passed to the compiler. In a preprocessing process all the
comments line will be removed because it is for use not for machine. In this step macro expansion is done.
The preprocessor creates an intermediate file where some pre-written assembly level instructions replace the
defined constant or expression. In this steps file inclusion process is also done by #include statements.
2. Compiler : The code which is expanded by the preprocessor is passed to the compiler. The compiler converts
this code into assembly code. Or we can say that the C compiler converts the pre-processed code into
assembly code. In this phase compiler gives the information about any syntax error or warning available in
your code.
3. Assembler : The assembly code is converted into object code by using an assembler. The name of the object
file generated by the assembler is the same as the source file. The extension of the object file in DOS is '.obj,'
and in UNIX, the extension is 'o'. If the name of the source file is 'hello.c', then the name of the object file
would be 'hello.obj'. Here assembly level code is converted into a machine understandable code that in binary
code using an assembler. It is prewritten program that translate assembly code into machine code.
4. Linker : A Linker is a computer program that takes one or more object files generated by a compiler and
combines them into one, executable program. The linker is to link the object code of our program with the
object code of the library files and other files. The output of the linker is the executable file. The name of the
executable file is the same as the source file but differs only in their extensions. In DOS, the extension of the
executable file is '.exe', and in UNIX, the executable file can be named as 'a.out'.

20. WHAT IS ALGORITHM?
• An algorithm is a sequence of well-defined instructions for completing a task or solving a problem. An
algorithm is that it contains the finite set of instructions which are being carried in a specific order to
perform the specific task. It is not the complete program or code; it is just a solution (logic) of a
problem, which can be represented either as an informal description using a Flowchart or Pseudocode.

21. Algorithm Examples :
1. Convert from one unit to another. (feet, yards, kilometers, miles)
2. Find square of Number.
3. Print total income from items sold in the week.
4. Multiplication of numbers entered by the user.
5. Sort a list of names in alphabetical order.
6. Quickly Find name in list.
7. Merging of list.
8. Find highest number from 2 numbers.

22. Characteristics or properties of Algorithm
1. Precision – The steps are precisely stated (defined).
2. Uniqueness – Results of each step are uniquely defined and only depend on the input and the result of
the preceding steps.
3. Finiteness – The algorithm stops after a finite number of instructions are executed.
4. Input – The algorithm receives input.
5. Output – The algorithm produces output.
6. Generality – The algorithm applies to a set of inputs.

23. Guidelines/Notation for Developing an Algorithm
Following guidelines must be followed while developing an algorithm:
1. An algorithm will be enclosed by START (or BEGIN) and STOP (or END).
2. To accept data from user, generally used statements are INPUT, READ, GET or OBTAIN.
3. To display result or any message, generally used statements are PRINT, DISPLAY, or WRITE.
4. Generally, COMPUTE or CALCULATE is used while describing mathematical expressions and based
on situation relevant operators can be used.

24. Advantages of Algorithm
1. It is a stepwise representation of a solution to a given problem, which makes it easy to understand.
2. An algorithm uses a definite procedure.
3. It is not dependent on any programming language, so it is easy to understand for anyone even without
programming knowledge.
4. Every step in an algorithm has its own logical sequence so it is easy to debug.
5. By using algorithm, the problem is broken down into smaller pieces or steps hence, it is easier for
programmer to convert it into an actual program.
Disadvantages of Algorithm
1. Algorithm is Time consuming.
2. Difficult to show Branching and Looping in Algorithms.
3. Big tasks are difficult to put in Algorithms.

25. Algorithm 1: Algorithm to convert temperature from Fahrenheit to Celsius.
Input: F
Output: C
F: temperature in Fahrenheit
C: temperature in Celsius.
Step 1: Start.
Step 2: Read temperature (Fahrenheit) in F.
Step 3: calculate C=(5(F-32))/9.
Step 4: Display C as temperature in Celsius.
Step 5: Stop.

26. Algorithm 2: Sum of two numbers
Input : A,B
Output : Sum
A : First number
B : Second number
Sum : Addition of both number
Step 1: Start
Step 2: Input first number in A
Step 3: Input second number in B
Step 4: Sum=A+B
Step 5: Display value of sum
Step 6: Stop