Outline for May 23, 2008

Reading: Text, §6, 7, 10

1. Greetings and felicitations!
2. Device Hardware
   continued from last lecture
   1. Communication lines: simplex, half-duplex, full duplex
3. Example device driver: line clock, programmable clock
4. Example device driver: disk device driver
   1. virtual disk as a linear array of sectors, reducing latencies
   2. ordering outstanding disk requests:
      1. first come, first serve: saturation
      2. pickup
      3. shortest seek time first
      4. SCAN (elevator algorithm), LOOK
      5. N-Step SCAN, N-Step LOOK
      6. C-SCAN, C-LOOK
      7. sector queueing
5. Process Interface
   1. file; system calls (open, close, position file pointer, read, write, miscellaneous control commands)
   2. blocking: synchronous, asynchronous (latter requires a handler and a wait system calls)