OPERATING SYSTEMS

3. unit of CPU scheduling.
5. to achieve mutual exclusion in concurrent processes.
6. CPU from one process to another.
7. hardware signal that interrupts normal execution to handle I/O events.
8. method where CPU repeatedly checks I/O device status
9. that stores information about files in a file system.
13. lightweight process that shares resources within a process.
14. where two or more processes wait indefinitely for resources held by each other.
16. , The software that acts as an intermediary between user and computer hardware.
17. scheduling algorithm that serves requests in the order they arrive.
19. structure containing all process information.
20. of memory into fixed-size blocks in memory management.
21. to ensure no circular wait occurs in deadlock.
22. part of OS responsible for allocating CPU to processes.

1. section of code that must be executed by only one process at a time.
2. two modes in which modern OS operates — user mode and ______ mode.
4. where processes share data without proper synchronization.
10. The method by which data blocks are allocated to files.
11. ,Mechanism that allows OS services to be requested by user programs.
12. , OS structure in which each layer is built on top of lower-level layers.
15. scheduling algorithm that services requests in one direction only, then returns to start.
18. scheduling algorithm that moves the arm back and forth like an elevator.
21. technique allowing devices to transfer data directly to memory.