Assignment 1 questions.

  How does the operating system read the command line parameter for the disk?
  Does hardware have a variable for that?

The command-line arguments are part of the simulator; your operating system
never sees them.

  How do we use the disk command register to cause a disk interrupts?

Writing the disk command register starts the disk working; when the disk
finishes working, the disk raises an interrupt. The disk command register
doesn't directly cause an interrupt. For example, if the disk got into some
strange state where it never finished an operation, it would never raise an
interrupt even though the disk command register was written.

  The documentation says to do the way by writing either "read" and "write" to
  it and that is supposed to start the execution.

That's right, although it's Hardware.Disk.readCommand and
Hardware.Disk.readCommand .

  Right now the operating system calls "interrupt(Hardware.Interrupt.disk)"
  after loading the disk.

The operating system should never call interrupt(); only the simulator calls
it.
Received on Wed Feb 15 2012 - 20:13:50 EST