Drop Down MenusCSS Drop Down MenuPure CSS Dropdown Menu

Fundamental Chapter 2

Q.  Describe the classification of Computer?


Write a short note on the following.

i)                    Analog, digital, Hybrid Computers
ii)                  Super, Mainframe, Micro, Mini Computers
iii)                General, Special Purpose Computers

 Classification of Computers:-
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?


Operating System as resource manager. Describe.

 Ans :-  
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.

·        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.
·        Resource Sharing
·        Powerful and cheap microprocessor technology
·        Better services to users
·        Communication and information sharing

Functions of Operating System

Operating System as resource Manager

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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.


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.
  1. Low-Level Language
  2. High-Level Language
  3. Object Oriented Language
  4. 4GL Language or User Friendly Language
  5. AI ( Artificial Intelligence )

  1. 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.
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

  1. 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.
  2. 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.
  3. 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.

No comments:

Post a Comment