*Question* (for end of part A)
(20 minutes)

Write a short well thought out essay, about one page long, 
comparing and contrasting bus design issues and network design 
issues.  Be precise, and explain with as much detail as you can.  
Be very clear about what are the similarities, and what are the 
differences, and explain why the similarities or differences arise.

*Question* (for end of part C)
(10 minutes)

Suppose that a hard disk with ten heads has 500 sectors per
track and 10000 tracks per surface.  If each sector holds 512
bytes, what is the approximate capacity of the disk?

If the disk rotates at 10000 rp sec, what is the average rotational
delay in locating a sector?  Express your answer in microseconds.
If the machine clock runs at 1 GHz, how many machine cycles pass
during an average rotational delay?

What is a cylinder?  For the disk just described, what is 
the capacity of each cylinder?  If the disk can only read
one sector at a time, what is the minimum time required to
read an entire cylinder?

*End Questions*

*Answers for part C*

(I assume calculators are *not* permitted, and have chosen 
numbers accordingly (but also to be in realistic ranges!))

Capacity approximately 25GB.  
(Precisely 25 000 000 KB = 10 * 500 * 10000 * 0.5KB)

Average rotational delay 50 microseconds = 50 000 machine cycles.
(Average rotational delay = one half rotation = 
half of one ten thousandth of a second)

Cylinder:  the set of tracks that can be accessed without
moving the heads.  In other words, in our example, a cylinder
is ten tracks, one on each surface, which lie directly above
or below each other.  Yet another way of saying this is "the
set of tracks at a given radial position".  Capacity 2500 KB.
The minimum time required to read a cylinder is simply the 
time required for ten rotations which is one millisecond.

*End Answers*