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)

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