Operating System

What is operating system?

• Computer = set of resources
  • Processors, memory, I/O & communication devices
• OS
  • Enable use of resources
  • Manage resources
  • The low-level software that supports a computer’s basic functions, such as scheduling tasks and controlling peripherals
• Resources not limited to hardware

OS Model

Operating system components

• Processor scheduler
• Memory manager
• I/O manager
•  Inter-process communication manager
•  File system manager

Operating system booting

• Booting is a bootstrapping process that starts OS when the user turns on computer system
• Boot sequence is set of operations the computer performs when it is switched on that load an operating system
• During bootstrapping, the kernel is loaded into memory and begins to execute.
• A variety of initialization tasks are performed and then the system is made available to users
• The primitive loader program that can load and execute the boot program is called Bootstrap program, and it is typically stored in ROM.
• On start up, computer automatically reads the bootstrap program.
• The boot program is generally stored on disk with predetermined address, called boot sector.
• The boot program then loads the operating system into memory, this is called bootstrapping.