Multiprogramming

• CPU-bound system
• I/O-bound system
• Maintain more than one program in the main memory
• Sharing of time and space

Multiprogramming OS

• Requires addition of new hardware components
  • DMA Hardware
  • Priority Interrupt Mechanism
  • Timer
  • Storage and Instruction Protection
  • Dynamic Address Relocation
• Is more complex compared to a simple OS
• Must hide the sharing of resources between different users
• Must hide details of storage and I/O devices
• Requires a complex file system for secondary storage

Tasks of a multiprogramming OS

• Bridge the gap between the machine and the user level
• Manage the available resources needed by different users
• Enforce protection policies
• Provide facilities for synchronization and communication