Solution to HW #2.

1. PCB: Process Control Block. It stores information about the process.

2. Atomic operation

Either run to completion without interruption or not executed at all.
It is important since without atomic operations, any combination of 
execution order is possible, which will make it very difficult (if not 
impossible) to ensure correct execution of concurrent processes.
Read (reference or Load) and write (assignment or STORE) are basic 
atomic operations.

3. Too-much-milk problem

This solution is incorrect, because it is possible to have starvation,
if one process is gone for vacation.

4. Separation of policy and mechanism

It is desirable for flexibility. Policies are likely to change 
from place to place or time to time. In the worst case, each change 
in policy would require a change in the underlying mechanism, which 
is bad. A change in policy can be easily instituted if the mechanism 
were properly separated and policy independent.