CS 241 review

# pipe:

• a pipe is a FIFO queue allowing two processes to communicate
• read, write request will be blocked if the pipe is empty or full

# file permission

• owner/group/other: eg. 664: owner+group can read and write, other can read
• read/write/exec(4/2/1): eg. read + exec = 5, read+write=6

# interrupt

• interrupt is a mechanism to improve processing efficiency

# concurrency

• concurrency is the sharing of resources in the same time frame

# asynchronous operation

• techniques to deal with events happened at unpredictable time or in unpredictable order

# advantages of virtual memory

1. address space can be larger than physical address(MainMEM as $ to disk)
   
2. simplify MEM management
   
3. protect address space for each process won't conflict with the other