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Top 10 List of Week 00

1. Operating System Definition
   Operating System is a program that acts as an interface between the user of a computer & the computer hardware. The goal of Operating System is to execute user programs and make solving user problems easier.

2. Interrupts
   Interrupt is a signal sent by controller when an event needs immediate attention. It alerts the processor to a high priority process requiring interruption of the current working process. In I/O devices one of the bus control lines is dedicated for this purpose and is called the Interrupt Service Routine (ISR) or interrupt handler.

3. Storage Structure
   Primary Storage is a storage that directly accessible by the CPU, faster, and volatile. E.g. Register, Cache, Main Memory. Secondary Storage is a Non Volatile storage that is not directly accessible by the CPU and have larger capacity. E.g. Non Volatile Memory, HDD. Tertiary Storage is a storage that usually used to store a large amount of data that is rarely used and it is the slowest memory. E.g. Optical Disk, Magenetic Tapes.

4. Cache
   Cache is a high speed memory that is used to reduce the average time to access data from the Main memory by storing copies of the data from frequently used main memory locations.

5. Dual Mode
   The dual mode purpose is to ensure the proper execution of the operating system. In dual mode there are two modes of operation. User Mode (Non privileged Mode) is run on behalf of user and can’t execute privilege instrucstion that may cause harm. Kernel Mode (Privileged Mode) can run privileged instruction such as handling interrupt and I/O management.

6. Security
   Security is measures used to defense the OS from attacks such as, worm, virus, malware, etc.

7. Protection
   Protection is a mechanism to control the access of processes or users to the system resources.

8. Process Management
   The operating system is responsible for scheduling processes and threads on the CPUs, creating and deleting both user and system processes, suspending and resuming processes, and providing mechanisms for process synchronization and process communication

9. Memory Management
   Memory management is the function responsible for keeping track of the status of each memory location, determines how memory is allocated among competing processes, decide which processes to load when memory space becomes available.

10. Mass Storage Management
    In Mass Storage Management, the operating system is responsible for mounting and unmounting, free-space management, storage allocation , disk scheduling, partitioning, protection. source : OSC Book