Problem 1
Describe the user interface in other hightechnology devices commonly found in the home or office, such as a smartphone, HD television, fitness watch, or microwave oven. Pick one specific device and discuss how well its interface is designed and how easy it is to use. Does the device use the same techniques as computer system interfaces, such as menus and icons?
Problem 2
Can you think of situations where you might want to see the underlying hardware of the computer system? That is, you want to interact with the actual machine, not the virtual machine. How could you accomplish this? (Essentially, how could you bypass the operating system?)
Problem 17
Is the following pair of statements legal or illegal? Explain why. LABEL: .DATA 3 LABEL: .DATA 4 If it is illegal, will the error be detected during pass 1 or pass 2 of the assembly process?
Problem 18
What are some drawbacks in using passwords to limit access to a computer system? Describe some other possible ways that an operating system could limit access. In what type of application might these alternative safeguards be appropriate?
Problem 20
Assume that any individual program spends about \(50 \%\) of its time waiting for \(1 / 0\) operation to be completed. What percentage of time is the processor doing useful work (called processor utilization) if there are three programs loaded into memory? How many programs should we keep in memory if we want processor utilization to be at least \(95 \%\) ?
Problem 21
Here is an algorithm for calling a triend on the telephone: Step Operation 1\. Dial the phone and wait for either an answer or a busy signal 2\. If the line is not busy then do Steps 3 and 4 3\. Talk as long as you want 4\. Hang up the phone, you are done 5\. Otherwise (the line is busy) 6\. Wait exactly 1 minute 7\. Go back to Step 1 and try again During execution, this algorithm could get into a situation in which, as in the deadlock problem, no useful work can ever get done. Describe the problem, explain why it occurs, and suggest how it could be solved.
Problem 22
Explain why a batch operating system would be totally inadequate to handle such modern applications as airline reservations and automated teller machines.
Problem 23
In a time-sharing operating system, why is system performance so sensitive to the value that is selected for the time slice? Explain what type of system behavior would occur if the value selected for the time slice were too large. What if it were too small?
Problem 24
As hardware (processor/memory) costs became significantly cheaper during the 1980 s and 1990 s, time-sharing became a much less attractive design for operating systems. Explain why this is the case.
Problem 26
The following four requests could come in to an operating system as it is running on a computer system: \- The clock in the computer has just "ticked," and we need to update a seconds counter. \- The program running on processor 2 is trying to perform an illegal operation code. \- Someone pulled the plug on the power supply, and the system will run out of power in \(50 \mathrm{msec}\). \- The disk has just read the character that passed under the read/write head, and it wants to store it in memory before the next one arrives. In what order should the operating system handle these requests?
