INTRODUCTION Flashcards
What is an operating system
An operating System is a collection of system programs that together control the operations of a computer system.
What are the objectives of the operating system?
The operating system offers users an appropriate interface to use the computer system.
It helps us to hide the information related to the hardware resources from the users.
The operating system provides the sharing of resources among users and programs in an efficient way.
The operating system helps us to manage the computer system resources.
The operating system offers convenient and impartial sharing of resources between the users and programs.
Briefly describe the evolution of the operating system
Serial processing
Batch processing
Multiprogramming
Time-sharing
Parallel system
Distributed system
Describe the basic elements of an operating system
Main Memory: - Main memory is also called Primary memory or Volatile memory. Main memory stores data and programs.
Processor: - A processor is defined as an integrated electronic circuit which performs the job of calculations in the computer. It performs input/output(I/O), arithmetical logical operations, and basic instructions that are passed from an operating system. The task of the processor is to control the processes in the computer and also perform data processing functions.
System bus: - System bus is the element of the operating system which is responsible for communication between the processors, I/O modules, and main memory.
I/O Modules: - The task of I/O modules is to move the data within the computer to its peripheral external environment.
List and briefly explain the different types of operating systems
- Batch Operating System –
This type of operating system does not interact with the computer directly. There is an operator which takes similar jobs having the same requirement and group them into batches. It is the responsibility of the operator to sort jobs with similar needs. - Time-Sharing Operating / Multitasking Systems –
Each task is given some time to execute after which the OS switches over to the next task. . Each user gets the time of CPU as they use a single system. The time that each task gets to execute is called quantum. - Distributed Operating System/ loosely coupled systems – A distributed operating system is system software over a collection of independent software, networked, communicating, and physically separate computational nodes. each node or system have same operating system
- Network Operating System/ tightly coupled systems/parallel systems– These types of operating systems allow shared access of files, printers, security, applications, and other networking functions over a small private network. All the users are well aware of the underlying configuration, of all other users within the network, their individual connections, etc. In the parallel system, a number of processors are executing the job in parallel. Network Operating System is a computer operating system that facilitates to connect and communicate various autonomous computers over a network.
- Real-Time Operating System –
These are used when there are time requirements that are very strict like missile systems, air traffic control systems, robots, etc. Two types:
-Hard Real-Time Systems:
Time constraints are very strict and even the shortest possible delay is not acceptable eg automatic parachutes or airbags
-Soft Real-Time Systems:
These OSs are for applications where for time-constraint is less strict. Here, a critical real- time task gets priority over other tasks and retains that priority
until it completes. Soft real time system can be mixed with other types of systems.
Give advantages, disadvantages and examples of distributed operating systems
Advantages of Distributed Operating System:
Failure of one will not affect the other network communication, as all systems are independent from each other
Since resources are being shared, computation is highly fast and durable
These systems are easily scalable as many systems can be easily added to the network
Delay in data processing reduces
Disadvantages of Distributed Operating System:
Failure of the main network will stop the entire communication
To establish distributed systems the language which is used are not well defined yet
These types of systems are not readily available as they are very expensive. Not only that the underlying software is highly complex and not understood well yet
Its maintenance is more costly because it is distributed across multiple servers.
Some time security issues can be arise while sharing data on entire networks
Examples of Distributed Operating System are- LOCUS, etc
Give advantages, disadvantages and examples of batch operating systems
Advantages of Batch Operating System:
Processors of the batch systems are aware of the time duration of the job even when it is present in the queue.
Batch systems can be shared by multiple users.
There I very less idle time of the batch system.
It enables us to manage the efficiently large load of work.
Disadvantages:
It is very difficult to debug the batch systems
It proves to be costly sometimes
If any job fails, then it is difficult to predict the time
Examples of Batch based Operating System: Payroll System, Bank Statements, etc.
Give advantages, disadvantages and examples of network operating systems
Advantages of Network Operating System:
It increases the throughput.
By increasing the number of processors(CPU), to get more work done in a shorter period of time.
Highly stable centralized servers
Security concerns are handled through servers
New technologies and hardware up-gradation are easily integrated into the system
Server access is possible remotely from different locations and types of systems
Disadvantages of Network Operating System:
Servers are costly
User has to depend on a central location for most operations
Maintenance and updates are required regularly
Examples of Network Operating System are: Microsoft Windows Server 2003, Microsoft Windows Server 2008, UNIX, Linux, Mac OS X, Novell NetWare, and BSD, etc.
Give advantages, disadvantages and examples of Time-sharing operating systems
Advantages of Time-Sharing OS:
Each task gets an equal opportunity
Fewer chances of duplication of software
CPU idle time can be reduced
It is possible to interact with the job when it is processing
Disadvantages of Time-Sharing OS:
Reliability problem
One must have to take care of the security and integrity of user programs and data
Data communication problem
Examples of Time-Sharing OSs are: Multics, Unix, etc.
Give advantages, disadvantages and examples of RTOS
Advantages of RTOS:
Maximum Consumption: Maximum utilization of devices and system, thus more output from all the resources
Task Shifting: The time assigned for shifting tasks in these systems are very less. For example, in older systems, it takes about 10 microseconds in shifting one task to another, and in the latest systems, it takes 3 microseconds.
Focus on Application: Focus on running applications and less importance to applications which are in the queue.
Disadvantages of RTOS:
Limited Tasks: Very few tasks run at the same time and their concentration is very less on few applications to avoid errors.
Use heavy system resources: Sometimes the system resources are not so good and they are expensive as well.
Complex Algorithms: The algorithms are very complex and difficult for the designer to write on.
Device driver and interrupt signals: It needs specific device drivers and interrupts signals to respond earliest to interrupts.
Thread Priority: It is not good to set thread priority as these systems are very less prone to switching tasks.
Examples of Real-Time Operating Systems are: Scientific experiments, medical imaging systems, industrial control systems, weapon systems, robots, air traffic control systems, etc.
Give some examples of operating systems
q LINUX and UNIX
q Mach
q MS-DOS
q MS-Windows (NT, XP, Vista, 7,8,10)
q Chicago, OS/2,
q MacOS
q Chrome OS
q Android OS
q iOS.
What are the different computer system components?
Hardware
provides basic computing resources (CPU, memory, I/O devices).
Operating system
Controls and coordinates the use of the hardware among the various application programs for the
various users.
Applications programs
Define the ways in which the system resources are used to solve the computing problems of the users (compilers, database systems, video games, business
programs).
Users (people, machines, other computers).
Draw an Abstract View of System Components
*See notes
Briefly describe serial processing and the the serial steps needed and its demerits
Before 1950, the programmers directly interact with the hardware there was no operating system at that time.
If a programmer wishes to execute a program on those days, the following serial steps are necessary.
-Type the program on punched card.
-Convert the punched card to a card reader.
-Submit to the computing machine, if there were any errors, the error is indicated by the lights.
-The programmer examined the register and main memory to identify the cause of an error
-Take outputs on the printers.
-Then the programmer ready for the next program.
Demerits: This type of processing is difficult for users, it takes much time and the next program should wait for the completion of the previous one.
Describe multiprogramming and its advantages
Multiprogramming is a technique to execute the number of programs simultaneously by a single processor.
In multiprogramming, a number of processes reside in main memory at a time.
Advantages
-Can get efficient memory utilization.
-CPU is never idle so the performance of CPU will increase.
-The throughput of CPU may also increase.
-In the non-multiprogramming environment, the user/program has to wait for CPU much time. But waiting time is limited in multiprogramming.
