Nt1330 Unit 3 Application Programming Case Study

1. Describe the functions of the kernel, service, and command layers of an OS. The kernel basically acts as the interface between hardware and applications. The kernel is also known as the engine or core of an OS, the outermost part of an operating system that interacts with user commands. Some of the kernel’s tasks are resource allocation, process management, memory management, input/output device management, and security management. It basically mediates access to system resources. The kernel is the vital center of a computer operating system. The service layer acts as a source to resources for application programs such as folder manipulation, input/output device access, starting/stopping programs, and creating, moving, and resizing GUI windows.

How and why does a thread move from the ready state to the running state? How and why does a thread move from the running state to the blocked state? How and why does a thread move from the blocked state to the ready state? A thread moves from the ready to running after it has been dispatched by the scheduler. The scheduler is the decision maker for preemptive scheduling, priority based scheduling, and real-time scheduling. Ready states are basically just waiting/idle states waiting on availability of the CPU. Once the CPU is available dispatch begins and the instructions are being executed.

A thread moved from running to blocked state when an error is given to the process, when the process requests another resource, or when the process is waiting for some event to happen before it proceeds. A process is put into a blocked state if it requests something for which it must wait. Once an interrupt is received the CPU will suspend the thread that is currently being executed by calling the supervisor to suspend

What is a process control block, and what is it used for?

A process block control is a data structure containing information about an active process. PCB is used for storing the collected information about the processes and allows the OS to locate key information about a process such as the name, state of the process, resources that are allocated to the process, scheduling information, process ID, and input/output devices that are used by the process.

7. What is a thread? What resources does it share with other threads in the same process?

A thread commonly referred to as a light weight process, is a portion of a process that can be scheduled and executed independently by the operating system. A thread shares primary storage, files, memory, and input/output devices all from their parent processes.

10. Describe the operation of virtual memory management.

Basically it is a method that the OS uses to minimize the amount of process code and data stored in memory by dividing pages and memory into frames. This also frees up the memory for other processes to use. Virtual memory management divides a program into partitions called pages. The virtual memory management feature allows your pc to compensate for physical memory shortages temporarily by transferring the data from RAM to disk storage. When a program is executing they are sent to a certain page frame and the rest are held in secondary storage. Pages that are needed in secondary storage will be copied to page frames. Since