About

Operating systems comprise a number of interdependent functions and principles. This web is an attempt to reflect that structure and connect various features appropriately. This may be more suitable than the (necessarily) linear presentation in a book-form.

Some major categories – similar to chapters – are outlined and articles are collected into these, although some articles may ‘appear’ in more than one category.

The articles here are intended to be ‘readily digestible’ and have mostly been kept quite short. Where feasible, figures and interactive demonstrations have been included to help with illustration.

Login

You are free to use the website as you wish. However, for full benefit, members of the University will need to log in, which enables the recording of ratings, requests for help, results and so forth.

We want to encourage anyone registered for the course to log in and record progress. We hope this is personally helpful in navigating through the course material. It is also useful feedback in that, if several people report not understanding some (important) topic during the term, we can do something about addressing the problem.

The Database

This logs your progress with most articles so you can keep track of your confidence in various subject areas. This is purely self-assessment and is not associated with any marks.

The staff (in principle!) can use digests of the map data to see if there are particular areas which need more attention for the whole cohort, as well as checking your individual needs.

A flag can be set in most articles as a request for specific TA help at the next weekly contact session. We will try to get a staff member to these requests as soon as possible. If there are many enquiries about the same article then we can revise these in a lecture session.

Other flags can be set to ‘bookmark’ articles to return to. You can find a list of these flags on your ‘Account’ page.

A separate flag is included to let you mark progress independently for revision purposes. You can clear all of these flags from you account page when you start a round of revision and then use them to mark places you feel confident about.

Fuller details about Privacy are available.

Tables of Contents

The Contents page can display tables, akin to the contents of a book. These contents can be filtered by group and try to show articles in an appropriate order for study. The level of detail, as indicated by an article’s priority is adjustable.

If you are logged in it will also show your ratings and indicate any ‘dependencies’ – articles we suggest you familiarise yourself with first. Under ‘Stats’, you can also see your progress in different groups of articles and in the module as a whole.

The Maps

The maps show the structure of the module, article by article, with a controllable degree of connectivity to aid sensible navigation. Two forms of map are used:

The Contents page gives access to the large-scale maps. You can get ‘All’ articles here or restrict the views to preselected ‘groups’ which are a bit like chapters of a book. These maps are useful for an overview of the material you have covered but rather dense for detailed navigation.

Local area maps are provided within articles for showing the immediate context and getting from one to another.

The level of detail on each is controllable, to some extent.

• The associations maps attempt to show the more important links between related articles so that you can follow up in a particular direction.
• The dependencies maps are a subset of associations intended to highlight the boundaries of your exploration. The arrows indicate the directions in which we recommend you proceed. When logged in, if you have satisfied the dependencies for an article – but not yet rated it – it will be shown in white. Grey articles are those where you have not yet rated all the topics on which they depend.
  • Dependencies limits the view to articles leading to the current position.
  • Dependants limits the view to articles leading from the current position.
  • Context displays a mixture of both of the above links.

It is suggested that you follow dependencies in your first explorations to avoid being caught out by unfamiliar terms. Later – such as for revision – associations may help make more connections between topics.

When you are logged in, colouring is used to record your self-assessed understanding of articles so you can see – at a glance – areas where you may want to concentrate effort or explore new territory. As you mark your own degree of familiarity with a subject this should highlight different areas to explore. Your ratings are shown from red (read it - didn’t understand it yet) shaded through to green (all happy and understood). On local maps, blue is used to highlight your current position.

Articles

Articles try to give a reasonably short introduction to a particular topic. When you are logged in, articles are marked with a ‘priority’ value to help you identify important core topics and spot those added for more general, background interest; higher priority values indicate the more fundamental topics. Roughly speaking:

• 1: Obscure points for general interest; understanding is not important.
• 2: Hopefully helpful clarifications: useful to understand.
• 3: General articles covering quite important topics.
• 4: Important topics: should be read and studied.
• 5: Key areas and general principles: probably vital!

The article can record and displays your personal level of ‘comfort’ with that topic and allows you to flag up help – typically in your next contact ‘lab.’ session. (Please use this facility responsibly!) You can also set some bookmarking flags for your own convenience.

The body of each articles comprises text, figures and, in some places, interactive demonstrations which you can use as illustrations or simply as toys. There are additional hyperlinks inside articles to other articles and to outside pages.

Each rateable article concludes with a navigation map, some suggestions as to where to visit next and (another) request for feedback.

Groups

Groups are added as a navigation aid. The attempt to collect articles under a common heading in a similar way that topics are collected into chapters in a book. One difference from a book is that some articles appear in multiple groups, so when you’ve finished one group you might discover you’ve already started some others. Each group also has a key introductory article with the same name as that group.

Some of the groups, such as [Memory Memory] and [Processes Processes] are, indeed, very similar to book chapters. Other groups (e.g. [Concepts Concepts]) collect issues which cross the more traditional boundaries. In the latter there will be more associations of articles but fewer dependencies.

Paths

We will lead you through the map in a planned – and, hopefully, fairly logical – way as the module progresses.

Some other themed paths are also available and can be displayed on the maps. Treat these as alternative trails if you want to go exploring on your own.

There will be more of these, soon.

The Quizzes

There are some quizzes dotted around particular articles. These are there for you to test your understanding and give rapid feedback. Use them as much (or as little) as you like.

[Quizzes More details] are available.

Coursework Exercises

Programming/practical exercises are intended to be short illustrations of various principles which are, perhaps, best explained by experimentation. Some contain a final ‘puzzle’ element which may require some extra thinking.

Code to get you started should be downloadable or can be copied directly from /opt/info/courses/COMP25111/exercise_code/… These are indexed here.

We ask that you submit this work. Create a folder for your COMP25111 work and within that folder, create a folder for each assignment. Use ‘submit’ from that folder. Any further details will be in the specific coursework article. Of course, ask for help if you get stuck.

None of these exercises should take more than an hour or so per week (unless you decide to extend them for your own interest) and most are intended to take a lot less than that. We ask that you submit evidence you have made a serious attempt at any work; it doesn’t need to be a perfectly refined product to earn marks.

Dashboard

Your personalised [/comp251/dashboard dashboard] is there to help you navigate through your own reminders and identify areas you feel you need to revise. It also provides a crude progress graph for self-assessment.

Progress is evaluated from both your degree of understanding of an article and the course managers’ priority settings for the articles. You will make more rapid progress if you concentrate on higher priority articles first. You do not need to understand every article in all its details to reach 100% - so don’t go mad!

We hope that, with honest self-assessment input, this will give you an indication of your overall mark for the course might be.

No promises on this – we haven’t calibrated it in any way yet – but it should still prove useful or, at least, interesting to watch.

The dashboard also lets you see any bookmarks you may have set and tries to make some suggestions of articles you may want to look at next. (There is no compulsion to follow these – it a bit experimental at the moment: wander at will!)

Account

When logged in you have access to a page (‘Profile’) which summarises your overall progress against a background calendar which leads you the end of the module. This is to help you regulate your progress over the duration of the semester, including any vacation periods.

Remember: this is a tool to provide personal feedback, not a competition!

You also get a summary profile of the articles you have rated and some bookmarks for subjects you might want to return to.

External links

There is no way to cover ‘everything’ in a single module and you should not expect to do so. If you want to explore further, some external links have been included. We have added pointers to demonstrations and videos where we have found something we feel may be useful or entertaining. Searching the Web will find lots more references. If you find something which may warrant inclusion, let us know!

There are also plenty of [Books books] covering this subject area which have the space to go into greater depth (and, often, breadth) on many of the topics.

There is also some ‘treasure’ buried in some articles.

Examples

Rather than try to cover many different approaches to particular subject, this site tries to concentrate more on principles with particular illustrative examples. Where there can be choices, often [Unix Unix]-like examples are chosen; these should be available to our expected users. Once a principle is understood it should be relatively easy to apply these to other systems.

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Caution

This is a new presentation – on quite an old (but ever evolving) subject. We have had very little time to get this site into shape and there will be some rough edges and work still proceeding. Please bear with us! We are still working on it.

We believe that what is already present is a positive revision to the previous year and we hope the material is more accessible, in more than one sense of the word.

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You can help!

Please:

• report any problems
  • with the website mechanism
  • with articles – facts or clarity
• suggest new or better examples and links you may find
• contribute your own material – especially in the form of embedded applications – and join our roll of honour

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