Assignment 7

  1. Exercises 6.1, 6.2, 6.14. (Note the typo in 6.14 part a: it should say, “The PC has the value 100ten, the address of the sub instruction.”
  2. The following questions have to do with a disk drive that has the following parameters:
    • There are two platters, and both surfaces are used for data on both platters.
    • There are 25,000 tracks per surface.
    • There are 1,000 sectors on every cylinder (no cylinder zones). Each sector contains 512 bytes of data.
    • The disk rotation speed is 14,400 RPM.
    • Moving the heads requires 1 msec of acceleration time, 1 msec of deceleration time, and 0.5 msec for each track position moved.
    1. What is the total capacity of the drive? Note that there are two ways to answer this: (i) use standard units of measure, where 1G is 109, which is the conventional way to measure disk capacities, and (ii) use binary units of measure where 1G is 230, which is the conventional way to measure memory capacities other than disks. Answer both ways, and be sure to indicate which is which.
    2. What is the average seek time (head movement time)? Assume the operating system optimizes accesses so that 10% of the accesses require no head movement, 10% require moving the heads one track position, 10% require moving the heads two track positions, 10% require moving the heads three track positions, and 10% require moving the heads four track positions. Then, to simplify things, assume 25% require moving the heads ten track position and the remaining 25% requre moving the heads 100 track positions.
    3. What is the rotation time for this disk, in milliseconds, and what is the average rotational delay? Assume there is no sector cache on the disk and that the operating system accesses sectors in a random order.
    4. What is the average access time for this disk given the above parameters?