COSD Unit 2: Basic of Operating System PDF

## 2. Basic concept of operating system * What is an operating system? An operating system is an interface between a computer user and a computer hardware. The operating system is a software that performs all the basic task like file management, memory management, process management, handling inpu...

## 2. Basic concept of operating system * What is an operating system? An operating system is an interface between a computer user and a computer hardware. The operating system is a software that performs all the basic task like file management, memory management, process management, handling inputs and outputs and controlling devices such as disk drivers and printers. | System s/w | User | Application s/w | |-----------|--------|----------------| | | ↑↓ | | | | Operating System | | | | ↑↓ | | | Hardware - CPU RAM I/O | | | * Types of operating system: 1. **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 groups them into batches. - Each user prepares the job on an offline device like a P and submits it to the computer operators. | Job | Operating System | Batch | CPU | |-----------|--------------------|-------|-----| | Job 1 | Batch | | | | Job 2 | Batch | | | | Job 3 | Batch | | | 2. **Multi-programming operating system**: - Multi-programming operating systems can handle more than one program simultaneously. - They are kept in memory and any one of them can be in execution. This leads to a better utilization of resources. - It increases CPU utilization by organizing jobs so that CPU always has one job to execute. - Multi-programming operating systems can handle the mechanism of job scheduling and CPU scheduling. | Job | Memory Partition | Operating System | |-----------|-------------------|-----------------| | Job 1 | | | | Job 2 | | | | Job 3 | | | 3. **Multi-processing system**: - The CPU, register, cache and memory is arranged in a way that multiple CPUs/registers/caches are connected together and they all share the same memory space. - It executes multiple jobs at the same time and makes the processing faster. - It supports large physical address space and large virtual address space. - If one processor fails, then other processors should retry the process state so that execution of the process can continue. 4. **Multitasking OS**: - Multitasking OS is a simple multi-programming operating system with a round robin scheduling facility. - It can run multiple programs simultaneously. - There are two types of multitasking systems: 1. **Preemptive multitasking** 2. **Co-operating** | Browser | PIC - process | |---------|--------------| | | | | | Operating system | | | | | | CPU | 5. **Time-sharing operating system**: - Each task is given some time to execute so that all the tasks work smoothly. - This system is also known as multi-tasking system. - The task can be from a single user or different users also. - The time that each task gets to execute is called **quantum**. - After this time interval is over, the system switches over to the next task.  6. **Distributed Operating System**: - Various autonomous interconnected computers communicate with each other using a shared communication network. - Independent system processes their own memory unit and CPU.  7. **Networking operating system**: - This system runs on a server, and it provides the capability to manage data, users, groups, security, applications and other networking functions. - A network computing system is a collection of physical interconnected computers. - The OS of each interconnected computer must contain, in addition to its own standalone functionality, provisions for handling communication. This addition does not change the essential structures of the OS.  8. **Real-time operating system**: - This type of OS serves real-time systems. The time interval required to process and respond to input is very small. This time interval is called response time. - Real-time systems are used where there are time requirements that are very stream-like such as missile systems, air traffic control systems, robots, etc.