What is the main task of any OS? An operating system is a system for controlling a computer, its processes, internal memory, and user actions in general. We offer the reader a closer look at the OS from this aspect.
What is it?
Of course, first of all, the operating system is a management system. Here is a more complete definition of the OS: a complex of control and processing applications. On the one hand, they act as an interface between devices of a computing system and application applications, programs. On the other hand, the operating system is a system for managing certain devices, computing processes. That OS effectively distribute computing resources between computing processes, reliably organize the calculations in the system.
If we turn to the logical structure of a typical computing system, the OS will occupy an intermediate position between devices with their own microarchitecture, machine language, embedded firmware on the one hand, and application applications on the other.
As for software developers, the OS allows them to abstract from the features of the functioning and implementation of devices, providing the minimum necessary functional set.
In most computing systems, the operating system is the control system. This is the main, most important (and in some cases the only) part of the software system. If we turn to specific examples, then the most popular OS will be the Microsoft product - Windows (Windows).
Operating system management
Many are interested in the question, are there specialized programs for managing operating systems? This construction of the sentence is incorrect. After all, the operating system itself is a set of programs that manage computer resources that maintains a dialogue between the user and the device.
Therefore, there is "oil oil": management control. There is a set of applications that the operating system “manages”.
Key OS Features
Operating system - computer resource management. This is the main task of the OS. A set of the following functions follows directly from it:
- Execution of various program requests. Something like: input and output of information, starting and stopping applications and applications, freeing up, allocating memory, etc.
- Providing standardized access to peripheral devices (for example, an input / output device).
- Computer memory management: its distribution between active processes, the general organization of virtual memory.
- Control access to data that resides on non-volatile media. For example, on optical, hard drives and so on.
- Saving information about system errors.
- Providing user interface.
Command Languages - User Dialog
How is data management of operating systems possible? As in most interactive systems, the user can influence the functioning of the OS using special command languages.
What is this? Command language is a computer language in which a person interacts with an interactive system. Why command? Each line that is entered by a person on the terminal and sent to the system is perceived as a user command in relation to the OS.
If we consider the niche of command languages from the side of the general system of languages of human-computer interaction, then they will belong to the category of interpreted ones. Their antagonists are complimentary languages.
Consider the difference between them: a language is called complimented if it requires that any structure on it be so closed that it could provide the possibility of isolated processing without involving additional language structures. Otherwise, her understanding cannot be guaranteed. Interpreted languages are understandable without meeting this requirement.
Process management
Consider process control in operating systems. OS controls the following activities associated with them:
- Both creation and deletion of processes.
- Synchronization.
- Planning.
- Communication.
- Resolution of deadlocks.
It should be noted that during its “life” the process repeatedly changes its own state:
- New. Just created process.
- Performed. Program commands at this time are executed in the CPU.
- Awaiting. The process is waiting for an event to complete. Most often, the latter is an I / O operation.
- Ready. A process that is waiting for the CPU to free.
- Completed. A process that has fully completed its work.
Note that the transition from one such state to another cannot be arbitrary.
In many operating systems, information about each process is stored in a special table of operational processes. Each of them is represented in the operating system by a specific data set. This is a set of values, parameters that characterize the current state of the process. It is used by the OS to control the passage of a specific process through a computer.
How is the computational process created in this case? There are two ways: directly entered from a keyboard command or through a batch file. The process includes at least downloading the application and creating special control blocks.
As a result of this, a qualitatively new process appears, which is later included in the multiprogramming mix. After that, the OS is already starting to see it. The process itself is in a state of readiness.
OS process table
Processes thus function, operate under the control of the operating system. Imagine a brief table of OS processes:
- Section "Process control": registers, instruction counters, stack pointers, process status, its priority, scheduling parameters, process identifiers, parent processes, process groups, process start time, processor time used.
- Section "Memory Management": pointers to text segments, pointers to data segments, pointers to stack segments.
- "File management": working directories, root directory, user identifiers, file descriptors, group identifiers.
Memory management
Let’s look at another important aspect: memory management in operating systems.
It should be noted that memory is the most important resource, which requires the most careful management by multi-program OS. What ensures its special role? The processor can execute instructions of applications, programs only if they are in computer memory.
In the early OSs, memory management was simple: the program and its necessary data were downloaded from some external data storage device (optical disk, punched tape, magnetic tape, etc.) to the computer's memory. With the advent of multiprogramming, the situation has fundamentally changed. A new task has arisen: allocating computer memory between several running applications.
The main tasks of the OS on memory management
We continue to talk about controls in operating systems. Let us single out the main tasks of the OS for managing computer memory:
- Tracking segments of free and occupied memory.
- Allocation of memory to certain processes and its release upon their completion.
- The crowding out of both codes and process data from RAM to disk is full or partial. It is used when the amount of main memory is not enough to accommodate all processes in it. When the OP is freed, the operating system returns the processes to their place.
- Setting addresses of programs and applications to specific zones of physical memory.
Additional OS features for managing PC memory
Consider the additional tasks that the system performs in this case:
- Dynamic allocation of device memory. This means fulfilling application requests to allocate an additional memory tank for them at runtime.
- Creation of new information service structures - buffers, descriptors of flows and processes.
- Memory protection. It consists in not allowing a particular process being executed to write or read data related to another action.
As we have already said, RAM is not enough for all processes. Therefore, the OS connects an external, disk. This consists of the following system actions:
- Swap. Here the process is fully loaded into memory for further work.
- Virtual memory. In this case, the process is partially loaded to perform some task.
Once again, large processes are only temporarily unloaded by the OS onto the hard drive. After the "RAM" is released, the system returns them to their places again.
An operating system is a whole complex of software that manages a computer. That is, his memory, processes, resources. Another important function of the OS: to build the interaction of a computer system with a person, a user. This is achieved by using special tools - command languages.