A Virtual Operating System (VOS) is a multiprocessing operating system designed for critical online computing. VOS combines power, flexibility, and efficiency within a fault-tolerant architecture. Some features of a VOS include multi-tasking, multi-threading, and kernel locking.
Multi-tasking means that the computer is doing multiple things at once.
Ex1: Running Winamp and Photoshop.
Ex2: Surfing the net and talking on AIM
Ex3: Virus scanning the hard drive and playing Princess Maker 2
Multi-threading is an individual process that can do more than one things at once. When a new thread is created, data is shared between the new thread and its parent. This is how it differs from multi-tasking.
Ex1: Matrix multiplication
Ex2: User login authentication
Ex3: Issuing the Linux clone() operation
The kernel can be protected by using locks. A thread accesses the kernel, then locks the kernel while it is accessing it, and finally unlocks it when it is done. All other threads must wait until the kernel is unlocked to access it.