I.
COMPUTER
FUNDAMENTALS:
CHARACTERISTICS
OF COMPUTER
1. High
speed: Computers have the ability to perform routine
tasks at a greater speed than human beings. They can perform millions of
calculations in seconds.
2. Accuracy:
The computer accepts large amount of data and performs specified
calculations and produces accurate results. Some people comment that computers
also make mistakes. But it is not. It is the mistake on the part of human
beings. The mistake might have happened because of wrong input or wrong program
given by the human beings.
3. Storage:
Computers can store large amount of
information. Any item of data or any instruction stored in the memory
can be retrieved by the computer at lightning speeds.
4. Automation:
Computers are capable of executing the
programs without the need of human intervention, the computer execute programs
one by one automatically.
5. Diligence:
Computers can perform the same task repeatedly
& with the same accuracy without getting tired. A computer will work
with same tempo from beginning to end.
6. Cost
effectiveness: Computers reduce the amount of paper
work and human effort, thereby reducing costs.
Register is used to quickly accept, store, and transfer data
and instructions that are being used immediately by the CPU.
· AC
Or Accumulator,
· Data
Register Or DR,
· AR Or Address Register,
· Memory
Data Register (MDR) ,
·
Index Register,
· Memory
Buffer Register.
Accumulator:
This register is
used for storing results those are produced by the system. When CPU will
generate some results after the processing then all the results will be stored
in to AC Register.
Data
Register:
This register is
used in micro computers to temporarily store data being transmitted to or from
peripheral device.
Address
Register:
This register
holds the memory address of data and instructions. This is used for access data
and instructions from memory during execution phase of an instructions.
Program
Counter:
It is commonly
called the instruction pointer in inter X86 microprocessor. It keeps track of
the next memory address of the instruction that is to be executed once the
execution of current instruction is completed.
Memory
Data Register:
MDR is the
register of a computer’s control unit that contains the data to be stored in
computer storage (RAM).It acts like a buffer and holds anything that is copied
from the memory ready for the processor to use it.
Index
Register: (Base Register)
A hardware
element which holds a number that can be added to the address portion of
computer instruction to form an effective address.
Memory
Buffer Register:
This is register
holds the contents of data and instructions read from memory or written in
memory.
II.
PLANNING THE COMPUTER PROGRAM:
PROBLEM SOLVING
Solving
problems is the core of computer science. Programmers must first understand how
a human solves a problem, then understand how to translate this
"algorithm" into something a computer can do, and finally how to
"write" the specific syntax (required by a computer) to get the job
done. It is sometimes the case that a machine will solve a problem in a
completely different way than a human.
Computer Programmers are
problem solvers. In order to solve a problem on a computer you must:
1.
Know how to represent the information
(data) describing the problem.
2.
Determine the steps to transform the
information from one representation into another.
PROBLEM DEFINITION: Design a program that will allow a user to Input a list of your family
members along with their age and state where they reside. Determine and print
the average age of your family and print the names of anyone who live in Texas.
Program
design: Program design is
both a verb and a noun.
It is the process that organizations use to develop a
program. Ideally, the process is collaborat ive, iterative, and
tentative—stakeholders work together to repeat, review, and refine a program
until they believe it will consistently achieve its purpose.
A program design is also the plan of action that results
from that process. Ideally, the plan is developed to the point that
others can implement the program in the same way and consistently achieve its
purpose.
DEBUGGING:
In computers,
debugging is the process of locating and fixing or bypassing bugs (errors) in computer program code .To debug a program or
hardware device is to start with a problem, isolate the source of the problem,
and then fix it. A user of a program that does not know how to fix the problem
may learn enough about the problem to be able to avoid it until it is
permanently fixed.
Debugging is a
necessary process in almost any new software or hardware
development process, whether a commercial product or an enterprise or personal
application program.
TYPES OF ERROS:
Types of program errors
We
distinguish between the following types of errors:
1.
Syntax errors:
errors due to the fact that the syntax of the language is not respected.
2.
Semantic errors:
errors due to an improper use of program statements.
3.
Logical errors:
errors due to the fact that the specification is not respected.
From
the point of view of when errors are detected, we distinguish:
1.
Compile time errors:
syntax errors and static semantic errors indicated by the compiler.
2.
Runtime errors:
dynamic semantic errors, and logical errors, that cannot be detected by the compiler
(debugging).
DOCUMENTATION:
In computer
hardware and software product development, documentation is the information
that describes the product to its users. It consists of the product technical
manuals and online information. The term is also sometimes used to mean the source information about the
product contained in design documents, detailed code comments, white papers,
and blackboard session notes.
Comments:
There are two
types of comments statements. They are
1. Single line comment
2. Multi line comment
Single
line comment:
In
Python, we use the hash (#) symbol to start writing a comment. It extends up to
the New line character.
Ex: # this is single line comment
Multiline comment: Another way of doing this is to use triple
quotes, either ''' or """. These triple quotes are generally
used for multi-line strings.
Ex: ‘’’ this is multi line comments
We are
learning python….
Thank
you….’’’
III.
TECHNIQUES OF PROBLEM SOLVING:
ALGORITHM
1.
A sequential (step by step)
solution of any program that written in human language, called algorithm.
2.
Algorithm is first step of the
solution process, after the analysis of problem, programmer writes the
algorithm of that problem.
Q. Write algorithm
and flowchart to input temperature, if temperature is less than 32 then print
"below freezing" otherwise print "above freezing"?
ALGORITHM:
step 1 : start
step 2 : input number is temp
step 3 : if (temp<32)
{
Printf(“below freezing”);
Else
Printf(“above freezing”);
}
step 5 : stop
FLOW CHART
Flow chart is a graphical or
symbolic representation of a process. Each step in the process is represented
by a different symbol and contains a short description of the process step. The
flow chart symbols are linked together with arrows showing the process flow
direction.
Common Flowchart Symbols
Different flow chart symbols have different meanings. The most
common flow chart symbols are:
·
Terminator: An oval flow chart shape indicating the start or end of the
process.
·
Process: A rectangular flow chart shape indicating a normal process flow
step.
·
Decision: A diamond flow chart shape indication a branch in the process
flow.
·
Connector: A small, labeled, circular flow chart shape used to indicate a
jump in the process flow. (Shown as the circle with the letter “A”, below.)
·
Data: A parallelogram that indicates data input or output (I/O) for a
process.
Decision
tables are compact (beautifully) and precise (frankly) ways of modeling
complicated logic, such as that which you might use in a computer program. They
do this by mapping the different states of a program to an action that a
program should perform. Decision tables take on the following format:
|
The
four quadrants
|
|
|
Conditions stub
|
Condition entries
|
|
Actions stub
|
Action entries
|
The limited-entry decision table is the
simplest to describe. The condition alternatives are simple Boolean values, and
the action entries are check-marks, representing which of the actions in a
given column are to be performed.
|
Example:
Decision Tables
A computer game example, for a
football simulation the following rules are set up.
What happens when:
1.
90 minutes up
2.
the game is a draw
Answer: Keep Playing and give them some extra time
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STRUCTURED PROGRAMMING CONCEPTS:
Procedural Programming Languages: These languages code programs in such a way that the program
executes statement by statement, reading and modifying a shared memory.
Examples: Pascal, FORTRAN, COBOL
The structured programming concept was formalized
in the year 1966 by Corrado Böhm and Giuseppe Jacopini.
Structured programming (sometimes known as modular programming) is a
subset of procedural programming that enforces a logical structure on the
program being written to make it more efficient and easier to understand and
modify.
Structured programming is not only limited to the top down
approach. It employs methods using:-
1.
Top down analysis for problem solving:
It focuses on dividing the problem into sub parts and hence simplifies the
problem solving.
2.
Modularization for program structure and organization:
It organizes large instructions by breaking them into separate and smaller
section of modules, sub routines and subprograms.
3.
Structured code for the individual modules:
Control structures are used to determine the exact order in which the set of
instructions are to be executed. Therefore, a structured code does not involve
GOTO statement as it represents no certain order of execution.
Example ALGOL, Pascal, Pl/I, C , Ada
