by Dinesh Thakur Category: Operating System

Computers are asked to store massive amounts of information on storage media such as floppy disks and hard disks. Long ago, the computer just saved all the files on the disk, and if you weren't careful, you could end up with a list of files so long you could strain your wrist just trying to scroll through them all! It was kind of like putting all the papers into your filing cabinet without folders.



 
by Dinesh Thakur Category: Operating System

A command interpreter, or command processor, is that crucial part of the operating system software that interprets, or processes, the commands you give, and then carries them out for you. In DOS, the command processor is usually COMMAND. COM, although DOS lets you substitute another command processor if you want. This sounds pretty technical and scary, but it really isn't difficult.



 
by Dinesh Thakur Category: Operating System

Cipher textis information that has been changed into secret code for security reasons. A scheme for encoding messages to prevent them being read by unauthorized persons. It may have been enciphered,encrypted,or encoded, but it all means the same thing: it doesn't look like English so no one can use the information unless they have thepasswordto decode it.



 
by Dinesh Thakur Category: Operating System

OS/2 stands for operating system/2, an operating system that was developed by Microsoft C01poration and IBM, and now being improved and marketed exclusively by IBM. OS/2 runs on 286-, 386-, and 486-based IBM PCs and compatibles. OS/2 has many of the same commands as DOS, can read DOS disks, but it is more sophisticated than DOS. In particular, OS/2 is a multi-tasking, multi-threaded operating system. Multi-tasking means it can run more than one application at a time; multi-threaded means that a single program can perform multiple separate tasks at the same time.



 
by Dinesh Thakur Category: Operating System

Cooperative multitasking A MULTITASKING scheme under which each concurrently running program must at intervals voluntarily relinquish control of the CPU to the next program. Such programs must be specially written to suspend themselves in some non critical section and so, conversely, programs that are not so written cannot be multitasked. This contrasts with PRE-EMPTIVE MULTITASKING in which the OPERATING SYSTEM itself periodically suspends each task, so that any program may be multitasked. Apple's MACOS is a cooperative multitasking system, whereas UNIX and WINDOWS are preemptive.

 
by Dinesh Thakur Category: Operating System

Definition: The operating system provides us a graphic interface to give the command to the computer system. But system can’t understand these commands directly. Translation of code into binary language done by the core component of an operating system (OS), i.e., KERNEL. User deal with the lowest layer of kernel and then kernel deal with system.



 
by Dinesh Thakur Category: Operating System

In operating systems like DOS and Unix, and in many text-based or character mode programs, you control what's happening by typing commands on a command line. The command line is simply the line on the screen where you type your commands. The only way to control an operating system or a program that uses a command line interface like this is by typing commands-you don't get menus, dialog boxes, or buttons.



 
by Dinesh Thakur Category: Operating System

BSD UNIX (Berkeley System Distribution) A family of versions of the UNIX operating system developed at the University of California at Berkeley in the early 1980s. BSD Unix version 4.0 was released in 1980 for DEC's VAX and PDP-ll computers. BSD Unix introduced many technical enhancements that have now been universally adopted, such as paged VIRTUAL MEMORY and built-in TCP/IP networking. It formed the basis for several commercial UNIX versions, including Sun's (prior to Solaris 2) and Hewlett Packard's ULTRIX.



 
by Dinesh Thakur Category: Operating System

Kernel and utilities

The operating system includes a number of routines (subroutines). the most important are the core or kernel. It is loaded into memory live at system initialization and contains many procedures needed to ensure system operation. Other routines, less critical, are called utilities.

The kernel of an operating system consists of four main parts: the manager tasks (or processes), the memory manager, and file manager IO Device Manager. It also has two auxiliary parts: charger operating system and shell.



 
by Dinesh Thakur Category: Operating System

The software is a kind of programs that enable a user to perform some specific task or used to operate a computer. It directs all the peripheral devices on a computer system - what to do and how to perform work. Without Software, we can’t operate hardware and perform any calculations. A computer system can be divided into three components: the hardware, the software and the users. The software can be further divided into mainly two parts: Application software and System Software. Bare use of hardware is not easy, so to make it easy software is created.



 
by Dinesh Thakur Category: Operating System

Definition: A Multi-user operating system is a computer operating system which allows multiple users to access the single system with one operating system on it. It is generally used on large mainframe computers.
Example: Linux, Unix, Windows 2000, Ubuntu, Mac OS etc.,
In the multi-user operating system, different users connected at different terminals and we can access, these users through the network as shown in the diagram.



 
by Dinesh Thakur Category: Operating System

Definition: System Software can be designed as the software in such a way so that it can control and work with computer hardware. It acts as an interface between the device and the end user.



 
by Dinesh Thakur Category: Operating System

Definition: A Scheduling Algorithm is the algorithm which tells us how much CPU time we can allocate to the processes.
These scheduling algorithms are either preemptive or non-preemptive.
Preemptive Scheduling Algorithms are those which are based on the priority of the processes. By preference, when a high priority process enters, it preempts a low priority process in between and executes the high priority process first.
Non-preemptive Scheduling Algorithms are those who can’t be preempted in between, i.e. we can not take control of CPU in between until the current process completes its execution.

 
by Dinesh Thakur Category: Operating System

Definition: Memory segmentation is the process in which we divide the primary memory of the computer into segments. It is a memory management technique. Each segment can be allocated to a process.
The segment table is the table which stores all the details about the segments which are further stored in one of the segments. Segment table contains two information about the segment: one is, the base address of the segment and other is, the length of the segment.



 
by Dinesh Thakur Category: Operating System

Definition: Priority Scheduling is a scheduling process which is based on priority. In priority scheduling, the scheduler himself chooses the task priority, and the process which has the highest priority is processed first as compared to other processes.

Example: Shortest Job First (SJF) scheduling

 
by Dinesh Thakur Category: Operating System

DefinitionPreemptive Scheduling is defined as the scheduling which is done when the process changes from running state to ready state or from waiting for the state to ready state. In this, the resources are allocated to execute the process for a certain period. After this, the process is taken away in the middle and is placed in the ready queue its bursts time is left and this process will stay in ready line until it gets its turn to execute.

 

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About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.



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