Q. Describe the classification of Computer?
or
Write a short note on the following.
i)
Analog, digital, Hybrid Computers
ii)
Super, Mainframe, Micro, Mini Computers
iii)
General, Special Purpose Computers
Ans:-
The classification of computers is based on the
following three categories:-
(1) According to Purpose
(2) According to technology used
(3) According to size and capacity.
(1) According to Purpose:- According to the utilization of compute for
different uses, computers are of following two types:-
(1)
General Purpose
Computers:- Computers that follow
instructions for general requirement such as sales analysis, financial accounting,
invoicing, inventory, management information etc are called general purpose
computers. Almost all computers used in
offices for commercial, educational and other applications are general purpose
computers.
(2)
Special purpose
computers:- Computers designed from
scratch to perform special tasks like scientific applications and research,
weather forecasting, medical diagnostic etc are called special purpose
computers.
(2) According to technology used:- according to the technology used, computes
are of following three types:-
(1) Analog computers:- Analog computers are special purpose
computers that represent and store data in continuously verifying physical
quantities such as current, voltage or frequency. These computers are programmed for measuring physical
quantities like temperature, speed etc and to perform computations on these
measurements. Analog computers are
mainly used for scientific and engineering applications. Some of the examples of analog computers are
given below:-
a) Thermometer:-
It is a simple analog computer used to measure temperature.
b) Speedometer:-
Car’s speedometer is another example of analog computer. Where te position of the needle on dial
represents the speed of the car.
Digital
Computers:- Digital computers are mainly
general purpose computers that represent and store data in discrete quantities
or numbers. In these computers, all
processing is done in terms of numeric representation (Binary digits) of data
and information. Although the user enter
data in decimal or character form, it is converted into binary digits (O’s and
I’s). Almost all the computers used now
a days are digital computers.
Difference between Analog and Digital Computers:-
Analog Computers
|
Digital Computers
|
Analog Computer accepts, processes and generates
continuous data (e.g. Air, Water, Distance)
|
The Digital Computer accepts, processes and produce
discrete data (e.g Age, Prices, Incomes etc)
|
Computation of Physical quantity.
|
Computation of numerical digits.
|
Accuracy of Computation is quite limited.
|
Accuracy of Computation is more.
|
Slow Systems
|
Fast Systems.
|
Used in limited number of applications.
|
Used in Unlimited number of applications.
|
Output is Continuous.
|
Output is obtained after complete computation is
carried out.
|
Measure & Answer (How much)
|
Counts & Answer (How much)
|
Hybrid Computers:-
Hybrid computers combine the technology of both analog and digital
computers. These computers store and
process analog signals which have been converted into discrete numbers using
analog-to-digital converters. They can
also convert the digital numbers into analog signals or physical properties
using digital to analog converters.
Hybrid computers are faster than analog computers but much slower than
digital computers. It find applications
is special areas.
For example:-
In a hospital, analog devices measure the heart functions, temperature
and other vital signs of the patients.
These measurements are converted into numbers and supplied to a digital
computer. This is used to monitor the
patient’s vital signs and it gives an immediately signal if any abnormal
reading is detected.
According to size and capacity:- According to size and memory/storage
capacity, computers are of following four types:-
Super Computers:-
Super computers is the biggest and fastest computer, which is mainly
designed for complex scientific applications.
It has many CPUs (central processing units- main part of computer) which
operate in parallel to make it as a fastest computer. These computers are very expensive and more
powerful than mainframe computers. It is
typically used fall the following applications:-
·
Weather
forecasting
·
Petroleum
Exploration and production
·
Energy Mgt
·
Defense
·
Nuclear Energy
Research
·
Weapons research
and development
·
Earthquake
prediction (seismology)
PARAM and ANURAG are Super Computers produced by
India. CRAY 3, CRAY-XMP 14, NEC 500, are
the another example of super computers.
Mainframe Computer:-
Mainframe computers are very large and fast computers but smaller and
slower the super computers. These are
used in a centralized location where many terminals (Input/Output devices) are
connected with one CPU and thus, allow different users to share the single
CPU. They have a very high memory
(several hundred megabytes) and can support thousands of users. These computers are faster and more powerful
than minicomputers. They are mainly used
for following applications:-
·
Railway and
Airline Reservations
·
Banking
Applications
·
Commercial
Applications of large industries/companies
Some examples of Mainframe Computers are- MEDHA
Series, DEC, IBM 3090, IBM 4381, IBM 4300 and IBM ES-9000.
Mini Computer:-
Minicomputers are medium scale, smaller and generally slower than
mainframe computers. Like Mainframes,
they have many terminals which are connected with one CPU and can support many
users. The cost of minicomputer is very
less as compared to mainframe. These
computers are faster and more powerful than microcomputers. These computer are suitable for medium class
organizations, banks, data processing centers etc.
Some of the examples of minicomputers are PDP-1, IBM
AS/400, and DEC MICRO VAX, IBM AS/400 is actually a midi computer (computer
with performance between a mainframe and minicomputer) is becoming very popular
among minicomputers.
Micro Computers:-
It is a low cost small digital computer.
This type of compute contains a microprocessor as its CPU, a memory
Unit, Input and Output device. These are
also called personal computer system.
Maximum speed of micro computers are up to 1 million bytes per second. These types of computers can be used to play
games, teach children math, make a painting, create net musical sounds etc.
They are very inexpensive families or home business
can offered to buy a small system to use at home.
Micro-Computers can be classified into the following
tow categories:-
·
Desktop Micro
Computes
·
Portable Micro
Computers
Desktop Micro Computers:- Common type of Micro Computes, which can
easily be accommodated on the top of a desk is called desktop computers. The usage of such computers is quite common
is offices, markets, homes etc.
Portable Micro Computers:- These Computes are small is size and looks
like a briefcase o a notebook. They are
very light in weight and easy to carry from one place to another. They use batteries or electronic current.
Examples of these computers are:-
·
Laptop Computers
·
Notebook
Computers
Laptop Computers sometimes called briefcase computes,
can be used on your lap and are very portable.
Like a desktop computers, laptop computers have a full typewriter
keyboard. Laptop computers can be
connected to larger peripherals. For
example- A regular size printer or a large monitor etc.
Notebook Computes are smaller is size than laptop
computers. These computers are idle for
user who have to wok away from their offices.
The users of these computers might be a student, a journalist and a
salesman etc. Example- IBM ThinkPad.
Q. Describe Operating System. What are various types
and functions of Operating System?
or
Operating System as resource manager. Describe.
Operating System:-
Operating system is a program that acts as an interface between the user
and compute hardware and controls the execution of all kinds of programs. It is the most important program in the
computer System. It is one program that
execute all the time always as the computer is operational and it exit only
when the computer is shut down. OS are
the programs that makes the computer work hence the name OS. It takes instructions in the form of commands
from user and translates into machine understandable instructions. It gets the instructions executed by the CPU
and translate the result back into user understandable form.
Definition:-
“An operating system is a set of programs, which are used to manage the
overall operations of a computer, in order to achieve maximum efficiency of the
computer system.” In other words, An
operating system is a large collection of software, which manages resources of
the computer system, such as memory, processor, file system and input/output
devices. It is the program with in a
computer system which helps users to run their applications.
The position of operating system in overall computer
is following:-
The diagram
clearly shows that the operating system directly controls computer hardware
resources and other programs depend on the facilities provided by the operating
system to gain access to computer system resources.
Types of operating system:-
The operating systems are classified as-
1. Single program operating system.
2. Batch processing system.
3. Multiprogramming operating system.
4. Multiuse or Multi-access operating system.
5. Multiprocessing operating system.
6. Real Time operating system.
7. Network operating system.
8. Distributed operating system.
Single Program operating system:- Single program operating system refers to
single pertaining to single user for example-MS-DOS. It has a single processor runs a single
program and interacts with a single use at a time.
Only one program resides in the computer memory and it
remains these till it is executed. It is
also called Uni Programmed operating system.
It is the simplest operating system because-
·
The whole memory
space is allocated to one program so memory management is not very difficult.
·
The CPU has to
execute only one program at a time so the CPU management also does not have any
problem.
Limitation:- In
single program operating system, the CPU remains idle most of the time because
as compared to CPU speed, the speed of I/O devices is quite slow.
Batch Operating System:- Jobs with similar requirements were batched
together and run through the computer as a group. The operating system handling
a batch of programs known as Batch or Concurrent operating system. This
operating system relieves the user from the difficult task of loading the next
program after the execution o a previous program is completed. It must be remembered that a batch program
operating system is a single program system because at a time only one program
is being executed by the CPU.
In this operating system:-
·
Memory is usually
divided into two parts. One part is fixed for containing operating system and
the other part contains use programs to be executed. When one program is executed, another program
is loaded into same memory area.
·
The CPU has to
execute only one program at a time, so the CPU management also does not have
problem.
Disadvantages:-
·
Non-Interactive
Environment:- Batch operating system
allows on interaction between users and executing programs.
·
High Turn around
Time:- The turn around time taken
between Job submission and completion is very high.
·
Off-Line
debugging:- This means that a programmer
can not correct bugs the moment it occurs.
Multi Programming Operating System:- Multiprogramming operating systems as
compared to batch operating system are fairly better but sophisticated. Multiprogramming increases CPU utilization y
organizing a number of jobs such that CPU always has one to execute.
Different forms of multiprogramming operating system
are:-
·
Multitasking or Multiprocessor
operating system
·
Time sharing
operating system.
Multitasking operating system:- A running state of a program is called a
process or a task. A multitasking
operating system supports more than one active process simultaneously with a
single CPU.It is also called serial multitasking or context switching which
implies stopping one temporarily to work on another.
In these operating systems, CPU switches from one task
to another so quickly that it gives the illusion to the use of executing all
the tasks at the same ties example- windows 95/98, windows NT etc.
Time-Sharing Operating System:- Time Sharing is a special case of
multiprogramming operating system with a quick response time. It allows many users to simultaneously share
the computer resources. It provides each
user with a small portion of a time-shared computer. In a time shared system since each action or
command take a very small fraction of time, only a little CPU time is needed
for each user.
As the CPU switches rapidly from one user to another
user, each user is given impression that he has his own computer, whereas
actually one computer is being shared among many users.
Multi user of multi-access operating system:- Multi user operating system allows
simultaneous access to a computer system through two or more terminals.
Example:-
Railway Reservation System & Airline reservation system support
hundreds of active terminals under control of a single program. Although it is associated with multiprogramming
multitasking operating system does not imply multiprogramming or multitasking.
Multiprocessing (Parallel) operating system:- In multiprocessing operating system,
multiple, CPUs perform more than one job at one time it differs from the
time-sharing operating system in the manner that it refers to utilization of
multiple CPUs.
In it the resources are allocated comfortable to the
competing processes in a manner which results in a high throughput eg:- UNIX,
MVS etc.Some mainframe and Supermini computers have multiple CPUs, each of
which can handle several jobs.
Real Time operating system:- Real Time system is a special purpose
operating system. It is used in those
environments, are accepted and processed in a short time, or within a specified
time. Real time operating system has
well defined, fixed time constraints.
Its main characteristics are:-
·
Fast response
time
·
Feedback
mechanism
·
Reliability
It has to handle a process within the specified time
limit otherwise the system fails, resulting in a disaster many a times. Such applications include- Scientific
experiments, flight control, few military applications, industrial control etc.
Network operating system:- a network operating system is a collection of
S/W and associated protocols that allows a set of computers which are
interconnected by a computer network to be used together. In a network operating system the uses are
aware of existence of multiple computers.
Capabilities of network operating system:-
·
Allowing users to
access the various resources of the network nodes.
·
Allowing the users
to copy files from one machine to another machine.
·
Controlling
access to ensure that only users in the proper authorization access particular
resources.
Distributed operating system:- A distributed operating system looks like an
ordinary centralized operating system that runs on multiple independent
CPUs. It is collection o processors that
do not shar memory. Each processor has
its own local memory.
The use of multiple processors is invisible to the
user i.e the users are not aware of where their programs are being run or where
there files are residing. These are
handled automatically and efficiently by the operating system.
Advantages:-
·
Resource Sharing
·
Powerful and
cheap microprocessor technology
Reliable
·
Better services
to users
·
Communication and
information sharing
Functions of Operating System
Operating System as resource Manager
- Process Management:- a process is an executable program. During execution, a process requires certain resources like CPU Time, Memory Space, and I/O Devices. At a particular instance of time, a computer system normally consists of a collection of processes. The process Management module of the operating system takes care of the creation and deletion of processes, scheduling of various resources to the different processes requesting them, and providing mechanisms for synchronization and communication among processes.
- Memory Management:- To execute a program, it must be loaded, together with the data is accesses, in the main memory. To improve CPU utilization and to provide better response time to its user, a computer system keeps several programs in main memory. The memory management module of an operating system takes care of the allocation and de-allocation of memory spapce to the various programs in need of the resource.
- File Management:- All computer systems are used for storage, retrieval and sharing of information. A computer normally stores such information in in units called files. Processes can read the information from the files and can create new files for storing the new information in the files. The file management module of an operating system takes care of file related activities such as organizing, storing, retrieval, naming, sharing and protection of files.
- Device Management:- A computer system consists of various I/O devices as terminals, printers, disks and tapes. The device management module of the operating system takes care of controlling all the computer’s I/O devices.
- Security:- Computer system stores a large amount of information, some of which is highly sensitive and valuable for their user. User can trust the system and rely on it only if the various resources and information of a computer system are protected against unauthorized access. The security module of the operating system ensures it.
- I/O Management:- operating system also manages input output devices. The function of input output devices is controlled by the operating system.
Scheduling:- operating system is responsible for the
scheduling of the input output devices.
Q. Give a complete
overview of computer languages.
Ans:-
Language:- it is a mechanism that
is used to exchange the ideas and thoughts between two or more entities. Like
we human being use so many sort of languages such as Hindi, English, French,
Japanese, Chinese etc. similarly to communicate with the machine we require
language. From the very beginning of the origin of the computer the languages
are developing side by side. There are so many types of computer programming
languages. We can classify them in to the following categories.
- Low-Level Language
- High-Level Language
- Object Oriented Language
- 4GL Language or User Friendly Language
- AI ( Artificial Intelligence )
- Low-Level Language:- they are the languages which are compatible with the machine not with human being means machine can understand these languages very easily but for human being they are difficult to understand.
Or
Using the low level languages it
is easier to develop the system software but the development of application
software is not possible.
There are two languages which
falls in the low-level language category:-
i.
Machine Language
ii.
Assembly Language
- High-Level Language:- they are the languages which are written in human understandable natural English language. For machine it is difficult to understand these languages directly. So some system utility called translators are used to convert the human understandable code into machine understandable code. They are Assembler, Compiler and Interpreter. Following are some example of high level language. BASIC, COBOL, FORTRAN, PASCAL etc.
- Object Oriented Language:- these languages includes some of the concepts of our real life like Class, Object, Abstraction, Inheritance, Poly-morphism, Encapsulation etc. some example of OOL are C++, Java etc.
- 4GL or User Friendly Languages:- these languages are easier to learn by the programmers and the development of the software is very quick. It supports the concept of RAD ( Rapid Application Development ). Visual Basic, Oracle are the 4GL Languages.
A.I. :- presently our researchers are working with the
generation of AI Programming Languages. These languages are used to develop the
intelligent machines which may behave in some way of human being like vision,
listening, speaking, thinking, walking etc. LISP, PROLOG are AI programming
languages which are used for Robotics and Expert System Development.
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