General, OS

What is the difference between a monitor and semaphore?

The reason that semaphores and monitors are needed is because multi-threaded applications (like Microsoft Word, Excel, etc) must control how threads access shared resources. This is known as thread synchronization – which is absolutely necessary in a multi-threaded application to ensure that threads work well with each other. If applications do not control the threads then it… Continue reading What is the difference between a monitor and semaphore?

General, OS

What is the difference between a thread and a process?

Processes vs Threads A process is an executing instance of an application. What does that mean? Well, for example, when you double-click the Microsoft Word icon, you start a process that runs Word. A thread is a path of execution within a process. Also, a process can contain multiple threads. When you start Word, the operating system… Continue reading What is the difference between a thread and a process?

General, OS

What is virtual memory, how is it implemented, and why do operating systems use it?

Real, or physical, memory exists on RAM chips inside the computer. Virtual memory, as its name suggests, doesn’t physically exist on a memory chip. It is an optimization technique and is implemented by the operating system in order to give an application program the impression that it has more memory than actually exists. Virtual memory is implemented… Continue reading What is virtual memory, how is it implemented, and why do operating systems use it?