After the upcoming Fall 2022 semester, the next time CSCI E-92 will be offered is in the Spring 2024 semester.
We will be holding our first section meeting on Tuesday, August 30, 2022 at 6:45 PM ET. Note that this section meeting is *before* our first class meeting. Both section and class meetings are live streamed and are also available after class for later viewing and reviewing.
Many links in the course website are not yet available. They will be activated as the course progresses.
Tuesdays 8:00-10:15 PM in 53 Church Street, Room L01. Students can attend in person on campus, participate live online at the time the class meets via web conference, or watch the recorded video on demand. Recorded sessions are typically available within a few hours of the end of class and no later than the following business day. Students who attend this course in person must comply with the Harvard Extension School mandatory COVID-19 immunization documentation policy. See COVID-19 Updates.Distance Learning Links including Video Streaming, Chat, and the Midterm Exam:
In addition to being able to participate in section & class in person, both are live streamed and also recorded. Students are encouraged to share their video feed and to ask questions verbally using their audio/video link in Zoom. The section & class live video stream is available through the class Canvas web site under Zoom.
Questions can also be asked using the text Chat facility in Zoom during class meetings & during section meetings. Please use the chat feature available in Zoom rather than Canvas chat. We will *not* be monitoring Canvas chat.After Class:
Videos of class and section are available on the course's Canvas web site under Class Recordings.Midterm Exam
Our midterm exam is a three hour long proctored exam that will be available on-line through Canvas with integrity protected by Proctorio. Students must start the exam within the 24-hour period that begins at the designated start time of our midterm exam and ends 24 hours later. Students will have three hours to complete the exam independent of when they start. More information will be available about the exam later in the semester.
The exam does not allow access to any books or notes, but relevant course slides will be made available. No electronic devices are allowed.Prerequisites:
Knowledge of data structures and programming experience, such as is taught in CSCI E-22 (formerly CSCI E-119) (Data Structures), is required. Experience using UNIX/Linux or equivalent at the shell level and the system programming level is strongly recommended, but not required. Students must have sufficient experience to write programming projects of modest size and complexity in the C Programming Language that utilize a variety of data structures. This course does *not* teach programming.Brief abstract:
This course examines the role of operating systems: process synchronization and scheduling; memory management including virtual memory, swapping, paging, and segmentation; file management; protection and security; input/output techniques, buffering, and resource allocation; deadlock detection and avoidance; system modeling; performance measurement and evaluation; and operating system case studies. An extensive lab project will be required of all students.
4 credits. Graduate credit.Overview:
Computer Science E-92 is a detailed exploration of the internal algorithms and design of operating systems. Students are expected to be comfortable with designing, coding, and debugging programs of reasonable complexity while employing good programming style and structured techniques. In particular, knowledge of C, terminal and text file I/O, classes, and data structures is presumed. During this class, students will use some UNIX system calls to complete the assignments.
A significant portion of the class will involve the design and implementation of a major term project. The project will be developed by each student working alone. That project is the core of a new operating system implemented from scratch for an ARM processor. Initially, both the classroom lectures and the section meetings will be covering material important to the design and implementation of the final project. Later in the semester, advanced topics will be covered in class; however, both the class and sections will continue to support students as term projects progress. For the term project, students will continue working on and debugging their projects leading to their complete implementation and a final demonstration.
Because the course includes a required and significant term project involving both programming and hardware implementation, the assignments will be time-consuming; therefore, a significant time commitment to the course is necessary. Although the relevant experience of students in the class is usually quite diverse, depending on background, it is not unusual for students to spend 10-15 hours per week or more completing the readings and homework assignments. Although the computers are available more-or-less around the clock, occasionally they will suddenly become unavailable (this is known as a crash). As with all such events, they always seem to occur at the worst possible time. Plan your computer work so that it is complete in advance of the deadlines. Check in your code to the required class git repository frequently. You have now been forewarned!Books/Course Bibliography:
All course books are available from the Harvard Coop and are available for on-line ordering. Keep in mind that Coop members receive a 10% discount. There are links available on Canvas to find the Library Reserves and, for some books, these include View online versions. In addition, all registered students will be eligible for library services (access, borrowing privileges, group study rooms) in FAS libraries, just like any other student in FAS. The Harvard Library website includes information about how to access library materials remotely as well as the reopening schedule. All registered students will continue to have access to Harvard Library on-line resources.
Modern Operating Systems, Fifth Edition; Andrew S. Tanenbaum and Herbert Bos; Prentice-Hall, 2023, 2014, 2008; ISBN-13 978-0-13-761887-3
Or, if the updated and preferred Fifth Edition is not accessible:
Modern Operating Systems, Fourth Edition; Andrew S. Tanenbaum and Herbert Bos; Prentice-Hall, 2015, 2008; ISBN-13 978-0-13-359162-0
Optional UNIX and POSIX Library Function Reference Books:
Advanced Programming in the UNIX Environment, Third Edition; W. Richard Stevens and Stephen A. Rago; Addison Wesley Professional, 2013; ISBN-13 978-0-32-163773-4
PThreads Programming: A POSIX Standard for Better Multiprocessing; Bradford Nichols, Dick Buttlar, Jacqueline Proulx Farrell; O'Reilly & Associates, Inc., 1996; ISBN-10 1-56592-115-1; ISBN-13 978-1-56592-115-3
Recommended C Language Reference Manual:
C: A Reference Manual, Fifth Edition; Samuel P. Harbison and Guy L. Steele, Jr.; Prentice Hall, 2002; ISBN-13 978-0-13-089592-9; Errata for the Third Edition from Sam Harbison; Our additional errata
Optional git Books:
Dangit, Git!: Recipes for Gitting out of a Git Mess; Katie Sylor-Miller and Julia Evans; This short on-line book describes git fundamentals.
Pro Git, 2nd Edition; Scott Chacon and Ben Straub; Apress, 2014; ISBN-13 978-1-4842-0077-3. This is a comprehensive book about git. It is also available for free download at the web site above.
There will also be other handouts & supplementary readingsInstructor:
We have two Teaching Assistants (TAs) for this course. The TAs hold a weekly section meeting and office hours as described below. Attendance at the TAs' section meeting is strongly recommended. Course material will be covered in section -- either in toto or in more detail -- that time does not permit to be covered in class meetings. For example, this material includes use of git and GitHub; general approaches to solving the problem sets; overviews of algorithms, code snippets, and data structures. Also, the section meetings provide a venue in which it may be easier to ask more lengthy questions. When appropriate to send e-mail, please send e-mail to both TAs and to the course instructor.
|TA||Section Meeting Time/Place||Office Hours Time/Place||E-mail Address/Phone|
6:45-7:45 PM ET,
53 Church Street, Room L01
6:30-7:30 PM ET,
Via web conference
|E-mail: ; +1.831.264.7805 (11:00 AM - 9:00 PM ET). If there's no answer, please leave a message with your name and a call-back number. Questions whose answers would be relevant to the whole class should be posed via Ed Discussion. When e-mail is appropriate (for grading questions, personal issues, etc.), e-mail should be sent to both TAs and also to the professor.|
6:45-7:45 PM ET,
53 Church Street, Room L01
6:30-7:30 PM ET,
Via web conference
|E-mail: ; +1.781.367.9690 (Weekdays: 10:00 AM - 9:00 PM ET; Weekends: 10:00 AM - 5:00 PM ET). If there's no answer, please leave a message with your name and a call-back number. Questions whose answers would be relevant to the whole class should be posed via Ed Discussion. When e-mail is appropriate (for grading questions, personal issues, etc.), e-mail should be sent to both TAs and also to the professor.|
When posing questions or bringing up issues of a non-personal nature, please use the class Ed Discussion Forum. Answers to questions posed on Ed Discussion benefit the whole class and allow the course staff to answer questions once for all students. Questions that include code or other information that shouldn't be shared with other students should be sent via e-mail to all course staff at the same time in order to increase the probability of a rapid response.Ed Discussion Wiki/Forum:
An Ed Discussion Wiki/Forum (on-line discussion list) for CSCI E-92 is set up at Harvard Extension School CSCI E-92 Ed Discussion Forum.Record a Say Hello! Video:
Using any tool of your choosing (perhaps a cell phone selfie or the camera on your laptop), please record and post a short video (maybe just one to three minutes in length) in Canvas Discussions as a reply to my Say Hello! discussion to introduce yourself to the class. With everyone being remote, anything we can do to create a community for our class would be great. Please tell us a little about yourself possibly including where you are located, your background, what you do when you're not taking classes, and your goals for this class.Enter Your Location:
Please enter your location in Canvas.Using git and GitHub:
When using "git" and GitHub, make sure to follow the information on using "git" and setting up your GitHub repository that is available on the section web site.Grading:
Graduate credit students:
All problem sets and programming assignments are due at midnight Eastern Time on Sunday night (i.e., midnight between Sunday and Monday) unless otherwise stated in the assignment or in the syllabus. Unless otherwise stated, all programming assignment solutions must be written in the C Programming Language. All code must build, be tested, and run on cscie92.dce.harvard.edu or on the NXP/Freescale K70 Tower computer systems, as appropriate; be submitted using "git" on GitHub (or, in dire circumstances, via e-mail only if agreed to by the course staff); be well-written (clear coding style, modular structure, appropriately commented and documented in English); and tested (include any programs and/or shell scripts used in testing your solution as part of your submission). Remember, in addition to handing in all parts of the problem set solution or programming assignment program, sample runs of the program which demonstrate that the program works must be attached. In addition, each submission must include a makefile to build the assignment. The grade for programming assignments will include all of these attributes.
Of course, the solutions may be written and tested using any system of the student's choosing; however, when the solution is complete, it must be tested on the cscie92.dce.harvard.edu computer and pushed to the git code repository on GitHub. You may choose to develop under your own Unix/Linux system or under Cygwin under Windows, but testing and grading of your programming assignments will take place on the cscie92.dce.harvard.edu computer. To reiterate, we will be grading the solutions based on their behavior on the cscie92.dce.harvard.edu computer.
The first step to begin to use our computer resources is to ensure that your HarvardKey account has been established. Use a browser to connect to https://key.harvard.edu. From that page, you can claim a new HarvardKey if you don't already have one. There, you can also manage your HarvardKey account. On the "Manage Your HarvardKey Account" page, in addition to your "Login Name," you can see your NetID. Your NetID will be required to login to our instance named cscie92.dce.harvard.edu.
Access to our cscie92.dce.harvard.edu instance requires that a VPN (Virtual Private Network) connection to the Harvard network is established first. The Cisco AnyConnect VPN application can be downloaded by logging into https://vpn.harvard.edu. Then, you can run the Cisco AnyConnect to complete the VPN connection. For creating the VPN, use vpn.harvard.edu as the hostname and click on "Connect." On the two-step verification pop-up window, enter your HarvardKey Login Name as your Username, and for the Password, enter your HarvardKey Password. Do *not* enter a Two-Step Verification Code. You should receive a request for approval via your Duo Mobile app before the VPN can be established.
After establishing a VPN connection to the Harvard network, you can set up an account on cscie92.dce.harvard.edu. Access our cscie92.dce.harvard.edu instance for remote login using "ssh" over the Internet. Your username is your HarvardKey NetID and your password is your HarvardKey password. On your first attempt to login to our instance, your account will be configured. Files may be transferred to these systems using "secure ftp" (SFTP). If you are using a Windows system, the SecureCRT and SecureFX programs are available from the Science Center at https://downloads.fas.harvard.edu/download; these programs implement "ssh" and "secure ftp," respectively. On Unix/Linux systems, the shell commands "ssh" and "sftp"/"scp" can be used for ssh and SFTP, respectively.
Separate documentation is available describing how to install and use git and GitHub on the section web site.
Some assignments may include Extra Credit programming problems. The Extra Credit programming problems can be completed to earn points that can increase the overall grade on the programming portion of your problem set; however, the grade on the programming portion of a problem set including extra credit will ever exceed the full credit possible grade on the programming portion. That is, the Extra Credit programming problem(s) can be used to make up for deficiencies in other programming portions of the problem set to allow a higher grade to be earned. Extra Credit points from one problem set are not transferrable and may not be used on any other problem sets.Late Policy:
All problem sets except for Problem Set 0 may be submitted late for partial credit. A late homework will lose 5% of its original grade for each day it is late (e.g. an assignment handed in two and a half days late will receive its original grade multiplied by 0.85). Late assignments may be submitted via "git" and an e-mail message notifying the instructor and the teaching assistants should be sent immediately after the late assignment is submitted. In addition, each student is given five free late days that may be used freely during the semester. However, keep in mind that almost all of the assignments are built on the previous assignments; handing in one assignment late does not extend the due date for subsequent assignments. The scope and difficultly level of the assignments increases during the class; therefore, we recommend against using the five free late days early in the class.
After a programming assignment has been initially submitted, we will award additional partial credit for corrections made to that assignment. We encourage students to correct any errors found in their code and to make improvements and enhancements. This will improve your grade and, in many cases, will be required to allow the next phase of your compiler to function correctly. No additional partial credit will be awarded for Problem Set 0 or for book problems.Commented and Documented:
In the "Grading: Problem Sets" section above, the phrase "commented and documented" is used; this paragraph will clarify the necessary comments and documentation that should be provided with all programs. First, there should be a description of the entire application. This should include the user interface (i.e., how a user interacts with the program) and an explanation of what the program does. This documentation may be in a separate file from the program itself. Second, there should be a description at the beginning of each file which outlines the contents of that file. Third, each routine, function, method, etc. must be preceded by a section describing: (1) the name of the routine, (2) the purpose/function of the routine, (3) the parameters to the routine (name, type, meaning), (4) the return value from the routine (type, meaning), and (5) any side-effects (including modifying global variables, performing I/O, modifying heap-based storage, etc.) that the routine may cause. Fourth, declarations of variables should be commented with their purpose. Fifth, blocks of code should be commented to describe the purpose of the code section. Sixth, any complex or difficult to understand code statements or fragments should be commented to clarify their behavior.Programming Languages:
In addition to programming in a conventional language (the C Programming Language), students will learn how to write code in ARM/Thumb assembly language. These are the low-level languages used by ARM computers. All students are required to use Special Edition CodeWarrior for Microcontrollers, Version 10.6 or Kinetis Design Studio (KDS), Version 3.2.0 from NXP/Freescale. This software may be downloaded from the www.nxp.com web site, is free, and no license is required. The Special Edition CodeWarrior for Microcontrollers software runs only on Windows. The Kinetis Design Studio software runs on either Windows, Mac, or Linux (DEB or RPM).Using git:
When using "git" and https://github.com/, make sure to follow the information on using "git" and setting up your repository that is available on the section web site. Create a named branch for each of your problem sets as follows: specify "problem-set-0" for Problem Set 0 (the course questionnaire, fix this program, and word count), specify "problem-set-1" for Problem Set 1, "problem-set-2" for Problem Set 2, etc., specify "project-proposal" for the Term Project Proposal, and specify "term-project" for the Term Project.Midterm Exam:
See Distance Learning Links: Midterm Exam for information on the Midterm Exam.Accessibility Services:
The Division of Continuing Education (DCE) is committed to providing an accessible academic community. The Accessibility Services Office (ASO) is responsible for providing accommodations to students with disabilities. Students must request accommodations or adjustments through the ASO. Instructors cannot grant accommodation requests without prior ASO approval. It is imperative to be in touch with the ASO as soon as possible to avoid delays in the provision of accommodation. DCE takes student privacy seriously. Any medical documentation should be provided directly to the ASO if a substantial accommodation is required. If you miss class due to a short-term illness, notify your instructor and/or TA but do not include a doctor's note. Course staff will not request, accept, or review doctor's notes or other medical documentation. Please visit https://www.extension.harvard.edu/resources-policies/accessibility-services-office-aso for more information, or contact firstname.lastname@example.org.Plagiarizing:
All work should be the personal creation of the individual student. Students are free to consult with each other and to study together, but all problem set solutions, programming assignments, exams, and the final project must be the personal contribution of each individual student. More explicitly, whenever a concept is reduced to a detailed algorithm or a program, no collaboration is allowed. If a paper, assignment, exam, program, or final project contains any information, algorithms, program fragments or other intellectual property taken from another source, that source and material must be explicitly identified and credit given. If you have any questions about this policy, it is the student's responsibility to clarify whether their activity is considered plagiarism.
You are responsible for understanding the Harvard Extension School policies on academic integrity and how to use sources responsibly . Not knowing the rules, misunderstanding the rules, running out of time, submitting the wrong draft, or being overwhelmed with multiple demands are not acceptable excuses. There are no excuses for failure to uphold academic integrity. Violations of academic integrity are taken very seriously. For more information on academic citation rules, please visit Using Sources Effectively and Responsibly and review the Harvard Guide to Using Sources.Publishing or Distributing Course Materials:
Students may not post, publish, sell, or otherwise publicly distribute course materials without the written permission of the course instructor. Such materials include, but are not limited to, the following: lecture notes, lecture slides, video, or audio recordings, assignments, problem sets, examinations, other students' work, and answer keys. Students who sell, post, publish, or distribute course materials without written permission, whether for the purposes of soliciting answers or otherwise, may be subject to disciplinary action, up to and including requirement to withdraw. Further, students may not make video or audio recordings of class sessions for their own use without written permission of the instructor.Course Outline:
|15||Registration opens at 9 AM for degree candidates|
|18||Registration opens at 9 AM for all students|
|15||Full payment deadline|
|26-September 6||Course change period for registered students only|
|30||First class meeting. Introduction, course information & policies, outline, schedule. Review of the C Programming Language. Devices. Abstractions provided by the operating system. Operating system structure.|
|4 at Midnight||Problem Set 0 (the course questionnaire, fix-this-program.c & word-count.c) due.|
|6||Course changes deadline; Course drop deadline for full-tuition refund|
|6||Second class meeting. Processes. Synchronization,
For today, read Tanenbaum 4/e chapters 1 "Introduction" and 2 "Processes and Threads".
|13||Course drop deadline for half-tuition refund|
|13||Third class meeting. Finish covering processes. K70 hardware platform. CodeWarrior development environment. Basic Electronics. Projects DataSizes, FlashLED, and Pushbutton. Distribute hardware.|
|18 at Midnight||Problem Set 1 due.|
|20||Fourth class meeting. Finish covering projects FlashLED
and Pushbutton. Memory management. Virtual memory, swapping,
paging, and segmentation.
For today, read Tanenbaum 4/e chapter 3 "Memory Management".
|27||Fifth class meeting. Input/Output systems, file systems,
buffering. Numerical encodings.
For today, read Tanenbaum 4/e chapters 4 "File Systems" and 5 "Input/Output".
|2 at Midnight||Problem Set 2 due.|
|4||Sixth class meeting. Finish covering Hamming Codes in
Input/Output systems. Serial Communication. Project
SerialIO. Introduce Deadlocks: definition, detection,
recovery, avoidance, and prevention.
For today, read Tanenbaum 4/e chapter 6 "Deadlocks".
|10||Indigenous Peoples' Day|
|11||Seventh class meeting. Application Notes. Deadlocks:
definition, detection, recovery, avoidance, and prevention.
Details of SerialIO project. Projects MCGInit, sdramTest, and
For today, review Tanenbaum 4/e chapter 6 "Deadlocks".
|16 at Midnight||Problem Set 3 due.|
|18||Eighth class meeting. Discuss UART2 problem on some Windows 10 computers and fix. Demonstrate UART2 use in SerialIO and in LCDRGB projects. Introduce concepts and code for using TWR-LCD-RGB, capacitive pads, A-to-D conversion, Supervisor calls, and privileged execution state.|
|25||Midterm exam. (Ninth class meeting.)
There will not be a usual class meeting held today. The
midterm exam will start at the time class would normally
begin. Students will have three hours to complete the exam.
Section will still be held today at its usual time, but no
material or questions relevant to the midterm exam will be
discussed in section today.
|30 at Midnight||Problem Set 4 due.|
|1-December 1||Degree program application period for fall|
|1||Tenth class meeting. Security and protection.
For today, read Tanenbaum 4/e chapter 9 "Security".
|6 at Midnight||Term Project Proposal due.|
|8||Eleventh class meeting. Introduction to parallel systems,
data parallelism, communication, gang scheduling.
For today, review Tanenbaum 4/e chapter 8 "Multiple Processor Systems".
|13 at Midnight||Problem Set 5 due.|
|15||Twelfth class meeting. Synchronization, threads, RPC.
System modeling, performance measurement and evaluation.
Introduction to distributed systems, DCE/Encina. Distributed
file systems. Fault tolerance, replication, redundancy. Case
study of UNIX/Linux/Android.
For today, review Tanenbaum 4/e chapter 2 "Processes and Threads". For today, read Tanenbaum 4/e chapter 10 "Case Study 1: Unix, Linux, and Android".
|18||Withdrawal deadline (no tuition refund)|
|22||Thirteenth class meeting. Case study of Windows 8/Windows
For today, read Tanenbaum 4/e chapter 11 "Case Study 2: Windows 8" or Tanenbaum 5/e chapter 11 "Case Study 2: Windows 11".
|29||Fourteenth class meeting. Operating system design,
Virtualization, and additional topics.
For today, read Tanenbaum 4/e chapter 7 "Virtualization and the Cloud" and chapter 12 "Operating System Design".
|4 at Midnight||Problem Set 6 due.|
|6||Fifteenth class meeting. Additional topics.|
|12-17||Final exams and last class meetings|
|13 by 4 PM ET||URL for ten minute pre-recorded final project presentation sent to course staff.|
|13||Final Class Meeting during usual section and class time. Student project presentations/demonstrations.|
|16 by 2 PM ET||Term Project report, slides, code, makefiles, test programs, etc. are due.|
|23-January 2, 2023||Winter Break|
|5||Grades available online in Online Services|
Hardware Related References:
The NXP/Freescale ARM:
This semester we will be using NXP/Freescale ARM development modules. Students will be required to purchase their own hardware for use during the class. Students must use the TWR-K70F120M processor board. (There is a TWR-K80F150M processor board, but it does not support a microSD card without requiring unsoldering and soldering of surface-mount printed-circuit board (PCB) components. These components are xmm x xmm and working with them requires specialized equipment.) The TWR-K70F120M processor, serial, and connector boards are available together as part TWR-K70F120M-KIT (this part includes TWR-K70F120M, TWR-SER, TWR-ELEV). Please do not purchase any hardware until consulting with the course staff. Additionally, some students may be able to use the following NXP/Freescale hardware: TWR-LCD-RGB, TWR-AUDIO-SGTL, TWR-ADCDAC-LTC, TWR-MC-LV3PH, TWR-RF-SNAP, TWR-SENSOR-PAK, TWR-SER2, TWR-WIFI-RS2101, and FSLBOT (includes TWR-MECH).
Hundredths of a second time at file creation time. This field contains a count of hundredths of a second. Because the seconds portion of the DIR_CrtTime field denotes a creation time with a granularity of 2 seconds, this field contains a number of hundredths of a second (0 to 199, inclusively) that denotes a number of seconds from 0 to 1.99, inclusively, that may increment the number of seconds in addition to supplying the number of hundredths of a second.
There is also a typo on page 25 where a field is referred to as DIR_CrtTimeMil (which does not exist, and, in any case, should be DIR_CrtTimeHundth!
USB to Serial Adapter:
Segger J-Link Debug Probe:
System files for the Kinetis K70F120M/MK70FN1M0 (120 MHz), GCC Toolchain:
System files for the Kinetis K70F120M/MK70FN1M0 (120 MHz), NXP/Freescale Toolchain:
Sample programs for the Kinetis K70F120M/MK70FN1M0 (120 MHz):
CSCI E-92 Application Notes for using the Kinetis K70F120M/MK70FN1M0 (120 MHz):
The Renesas Technology M16C:
The Renesas SKP16C62P StarterKit Plus is an evaluation kit for the M30626 microcontroller. The M30626 microcontroller contains an M16C processor core with memory, peripherals, and an LCD controller. The Renesas SKPCOMMS Communications Applications card is a daughter board for SKP StarterKits that adds SRAM, two RS-232 ports, Ethernet, and two CAN ports.
All system files and sample programs below zipped together: M16Cfiles.zip
System files for the M30626:
Sample programs for the M30626:
The Microchip Technology PIC:
The example PIC assembly language program, blink.asm, from class to blink the LED's.
Electronics stores in the Greater Boston Area:
Electronics distributors on the Web:
Hardware (as in nuts and bolts, etc.) distibutors on the Web:
Static dissipative devices used in the lab:
The ring terminal at the end of the common point ground wire should be attached to the nearest electrical outlet faceplace using the screw between the outlets of a duplex outlet. Note that the alligator clips connected to the wires on both the anti-static mat and the wrist strap are removeable. The alligator clips are actually adapters from banana plugs to alligator clips similar to . After the alligator clip adapter is pulled off, the banana plug can be plugged into one of the two banana jacks on the common point ground.
Software and Course Documents On-Line:
Slides used in class
The Course Questionnaire and Problem Sets
Online Software: GNU, Cygwin, etc.
Harvard University Information Technology
Online Papers Used in Class
Section Home Page