CS 505 - Operating Systems Concepts

Fall 2000

It was created in 1969 as a private research project in AT&T's Bell Laboratories by Ken Thompson and Dennis Ritchie. The interface--and I use that term loosely--was "borrowed" from Honeywell's MULTICS (which comes from MULTiplexed Information Computing System). The Bell guys also borrowed the naming concept to create UNiplexed Information and Computing System, which was originally spelled "UNICS."

"Uniplexed" would imply "one" to the multiplexed "many," suggesting that Unix was meant to be a single-user operating system. Nothing could be further from the truth. Almost every design decision has been aimed toward making Unix a multiplexed, multi-user OS.

Thus showing that you can't trust anything about Unix.

- David Every, An introduction to Unix
MacWeek, Thursday, 17 August 2000

Table of Contents

Course Description

This an introductory course in operating systems concepts. Check the course catalog entries for more information about CS 505.

You should be a proficient programmer and have a working knowledge of basic algorithms and data structures. The prerequisites for this class are Computer Science 503 (Advanced Programming I).

The course is divided into four three-week sections, with each section covering a major part of an operating system. See the syllabus for details.

The class meets in Howard Hall 522 on Mondays and Wednesdays, 6:00 p.m. to 7:50 p.m. There will be no classes on Wednesday, 22 November.


The objectives of this course are to learn the basics of operating systems: their structure, design and implementation. At the end of this course, you should:


R. Clayton, Howard B-13, rclayton@monmouth.edu, 732 263 5522. Office hours are Monday 11 a.m. to noon and Thursday noon to 1 p.m. in my office. I'm also usually happy to talk to you any time you can catch me; setting up an appointment is recommended, see my schedule for details.


There will be four tests, given at the end of each three-week section; see the syllabus for the schedule. Tests will be given in class, and are closed book with no notes; calculators and computers will not be necessary. The tests are cumulative, covering everything taught up to and including the class before the test. Tests should take no more than an hour to complete, and will be given in the first half of the class. Test answers will be made available off the syllabus.

There will be four programming assignments, one for each three-week section; see the project description for details.

There are no mid-term or final exams; for those that need them, mid-term grades will be computed as the straight, unweighted average of the test and programming assignment grades completed by the mid-term.

The final grade is a straight, unweighted average of test scores and programming assignment grades; that is, there are eight grades total - four from tests and four from assignments - and each grade constitutes one-eighth of your final grade.

I use the usual grade ranges:

95 <=A
90 <=A-< 95
86.6<=B+< 90
83.3<=B < 86.6
80 <=B-< 83.3
76.6<=C+< 80
73.3<=C < 76.6
70 <=C-< 73.3
F < 70
All grades are kept with one digit of precision to the right of the decimal point and 0.05 rounded up. No grades are adjusted to a curve; that means that 89.9 is a B+, not an A-.

The final grades.



The textbook is Operating Systems: Design And Implementation, second edition by A. Tanenbaum and A. Woodhull, Prentice Hall, 1997.

This is a programming course, and you will be writing C++ programs. It is probably a good idea to have on hand a book about C++ programming. If you're going to buy a book, I recommend the C++ Primer, third edition, by Lippman and Lajoie (Addison-Wesley, 1998). The department uses C++ How to Program by Deitel and Deitel (Prentice Hall, 1998) in its programming classes, and you'll be o.k. if you have or can borrow a copy to use.


You should feel free to send me e-mail. Unless I warn you beforehand, I'll usually respond within a couple of hours; if I don't respond within a day, resend the message.

Mail relevant to the class will be stored in a hyper-mail archive. If your message is of general interest to the class, I'll store it, suitably stripped of identification and along with my answer, in the archive.

Home page

If you're reading this on paper, you can find the class home page at http://www.monmouth.edu/rclayton/web-pages/f00-438-505/505-index.html. I'll make the class notes, assignments, and tests available off the syllabus; you should get in the habit of checking the home page and syllabus regularly.



People who need assistance or accommodations above and beyond what is usually provided in class should contact the University's ADA/504 coordinator to get those needs met. See me or the Disability Services page for more details.


I have no class attendance policy; you may attend class or not as you see fit. However, I hold you responsible for knowing everything that goes on in class; "I wasn't in class for that." is not an acceptable excuse for a wrong answer, or for giving no answer at all.

My attendance policy applies only to lecture attendance; it does not apply to other kinds of attendance which may be required for the course. Repeated failures to meet the attendance expectations set for tests, meetings, projects, labs or other forms of course work will have a bad influence on your grade.

Monmouth University does have a class attendance policy, which you can find in the Academic Information chapter of the Student Handbook. To the extent that I need to keep the record straight, I will take attendance. Attendance lists, however, are entirely for the University's benefit; I will make no use of them in grading.


Cheating's not nice; don't do it. Anyone caught cheating fails the course. The chapters on Academic Information and the Student Code of Conduct in the Student Handbook describe academic honesty and how it can be violated.

Complaining about Grades

I recognize and encourage a student's sacred right to complain about their grade. There are, however, a few rules under which such complaining should take place, and those students who don't follow the rules will be less successful in their complaints than those students who do follow the rules.

First, the only complaint that matters is that something got marked wrong when it was actually right. When you come to complain, be prepared to present, in explicit detail, what it is you did and why you think it's right.

Second, complaints about a particular test or assignment are only valid until the next test or assignment is due; after that point the book is permanently closed on all previous test or assignment grades.

Late Assignments

Assignments must be turned in by their due date; assignments turned in after their due date are late. You should contact me as soon as possible if you need to negotiate a due-date extension. The longer you wait to negotiate, the less likely it is you'll be successful; in particular, you have almost no chance of getting an extension if you try for one the day before the due date, and you have no chance of getting an extention on the due date.

A late assignment is penalized five points a day for each day it's late. I use a 24-hour clock running from midnight to midnight to measure days; note this means that an assignment handed in the day after it's due is penalized ten points: five for the day it was due and five for the next day.

Missing Tests

There may occasionally be a conflict between taking a test and doing something else, particularly among those working full time. If you're going to be out of town, or on jury duty, or whatever, on a test day, let me know beforehand and we'll discuss a make-up test.

A make-up test must be scheduled to be taken by the date of the test following the missed test (or the final exam if you miss the last test). If a missed test is not made up by the time of the next test, you get a zero for the missed test.

There will be only one make up given per missed test. If more than one person misses the same test, those people will have to coordinate among themselves to pick a mutually agreeable date for the make up.


The previous time I taught this course.

Other operating system courses.

Operating system projects and research.

An OS web ring.

Lists of resources for the Be OS.

Not for computers only: a pre-emptive, multitasking, open-source operating system for LEGO Mindstorms (and it supports POSIX semaphores too).

OS News, a web site with os news and opinions, and an example of how USA Today would cover operating systems if USA Today covered operating systems.

A FAQ on building your own operating system. It appears to be Linux and PC-centric, but it'll give you some idea of what you're missing when writing to a simulator.

A couple of real-time kernels, one based on POSIX threads, and the other using C++.

The ER and KeyK OSs from U. Penn.

And let us not forget the dearly departed: OS/2, VMS, and multics.

And let us welcome the newcomers: V2.

This page last modified on 29 December 2000.