Intro to computer

INTRODUCTIONTOCOMPUTER
B.Sc 1st Sem

Computer
 A computer is an electronic device, operating under the
control of instructions stored in its own memory that
can accept data (input), process the data according to
specified rules, produce information (output), and store
the information for future use.
 It performs the following three operations in sequence.
 1. It receives data & instructions from the input device.
 2. Processes the data as per instructions.
 3. Provides the result (output) in a desired form.

 The various functions of these units can be
summarized as:
1.Input device : Reads information from input media and
enters to the computer in a coded form
2.CPU
 (a) Memory unit : Stores program and data
 (b) Arithmetic Logic unit : Performs arithmetic and
logical functions
 (c) Control Unit : Interprets program instructions and
controls the input and
 output devices
3. Output device : decodes information and presents it to
the user

The basic parts of a computer are as follows −
 Input Unit − Devices like keyboard and mouse that are used to input
data and instructions to the computer are called input unit.
 Output Unit − Devices like printer and visual display unit that are
used to provide information to the user in desired format are called
output unit.
 Control Unit − As the name suggests, this unit controls all the
functions of the computer. All devices or parts of computer
 interact through the control unit.
 Arithmetic Logic Unit − This is the brain of the computer where all
arithmetic operations and logical operations take place.
 Memory − All input data, instructions and data interim to the
processes are stored in the memory. Memory is of two types –
primary memory and secondary memory. Primary memory
resides within the CPU whereas secondary memory is external to it.

Characteristics of Computer
 To understand why computers are such an important part of our lives,
let us look at some of its characteristics −
 Speed − Typically, a computer can carry out 3-4 million instructions
per second.
 Accuracy − Computers exhibit a very high degree of accuracy.
Errors that may occur are usually due to inaccurate data, wrong
instructions or bug in chips – all human errors.
 Reliability − Computers can carry out same type of work repeatedly
without throwing up errors due to tiredness or boredom, which are
very common among humans.
 Versatility − Computers can carry out a wide range of work from
data entry and ticket booking to complex mathematical calculations
and continuous astronomical observations. If you can input the
necessary data with correct instructions, computer will do the
processing.
 Storage Capacity − Computers can store a very large amount of
data at a fraction of cost of traditional storage of files. Also, data is
safe from normal wear and tear associated with paper.
 Diligence- Unlike human beings, a computer is free from monotony,
tiredness, and lack of concentration.It can work continuously without
any error and boredom.

Hardware Software
Hardware is a physical parts computer that
cause processing of data.
Software is a set of instruction that tells a
computer exactly what to do.
It is manufactured. It is developed and engineered.
Hardware can not perform any task without
software.
software can not be executed without hardware.
As Hardware are physical electronic devices, we
can see and touch hardware.
We can see and also use the software but can’t
actually touch them.
It has four main categories: input device, output
devices, storage, and internal components.
It is mainly divided into System software,
Programming software and Application
software.
Hardware is not affected by computer viruses. Software is affected by computer viruses.
It can not be transferred from one place to
another electrically through network.
But, it can be transferred.
If hardware is damaged, it is replaced with new
one.
If software is damaged, its backup copy can be
reinstalled.
Ex: Keyboard, Mouse, Monitor, Printer, CPU,
Hard disk, RAM, ROM etc.
Ex: Ms Word, Excel, Power Point, Photoshop,
MySQL etc.

Batch
processing
Batch data processing is an efficient way of processing high
volumes of data is where a group of transactions is collected over
a period of time. Data is collected, entered, processed and then the
batch results are produced (Hadoop is focused on batch data
processing). Batch processing requires separate programs for
input, process and output. An example is payroll and billing
systems, transactions of credit cards, generation of bills.
In contrast, real time data processing involves a continual
input, process and output of data. Data must be processed in a
small time period (or near real time). Radar systems,
customer services and bank ATMs are examples.

O LINE
PROCESSING
 Online processing systems are used all over the internet
nowadays. Small to enterprise web based and desktop
applications use online processing for their customers. For
example when we purchase something on internet then it is
handled by online processing systems.
 Advantages of online processing systems:-
 Easy to use to do shopping online
 These systems have quick response time
 It is easy to use just form filling and your job get processed
automatically by web and database servers
 Online banks nowadays use online processing systems for
money transactions
 Usage of credit cards is also handled by these systems
 You can access anything worldwide online and purchase it
on the spot by bank wire transfer, credit cards, and online
banks. All these systems are handled by online processing.

Batch Processing System Realtime Processing System
Jobs with similar requirements are batched together and run
through the computer as a group.
In this system, events mostly external to computer system are
accepted and processed within certain deadlines.
This system is particularly suited for applications such as
Payroll, Forecasting, Statistical analysis etc.
This processing system is particularly suited for applications
such as scientific experiments, Flight control, few military
applications, Industrial control etc.
It provides most economical and simplest processing method for
business applications.
Complex and costly processing requires unique hardware and
software to handle complex operating system programs.
In this system data is collected for defined period of time and is
processed in batches.
Supports random data input at random time.
In this system sorting is performed before processing. No sorting is required.
It is measurement oriented. It is action or event oriented.
Transactions are batch processed and periodically. Transactions are processed as and when they occur.
In this processing there is no time limit. It has to handle a process within the specified time limit
otherwise the system fails.

Intro to computer

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