I thought I’d find out a little more about some of the computing cornerstones that were laid in Manchester’s labs. Did you know that the first Random Access Memory was created there? Fast, random access memory is a core part of computer systems today. Having enough of it is crucial to making your laptop or desktop run all those applications quickly for you.

The Williams (or Williams-Kilburn) Tube was the first random access memory that could access at speeds suitable for a computer. It was the ancestor of the multi-gigabyte cards you’ll find in your computer today.

Back in the days before TVs were two inches thick, the moving pictures on the screen were drawn by magnetic fields and streams of electrons in a glass tube called a Cathode Ray Tube, or CRT. Did you ever hold your hand near the screen of a CRT television and feel the static tingle? Somewhere around 1946, Tom Kilburn and Freddie Williams at Manchester University used the charge on a CRT’s phosphorescent coating to store ones and zeroes (effectively as dots), where they could be detected by a ‘pickup plate’ which lay over the ’screen’.

As the electron beam hit the screen, a positive charge would be left behind at that position. Not for long mind you, as the charge would dissipate, but the information read by the pickup plate was used to refresh the tube before the charge had chance to leak away. This refreshing process is still required by the RAM chips in your computer today.

If you’re interested in knowing more, you can read all about it on Wikipedia and computer50.org, the sources I used to get this information.

To test the Williams Tube, the folks at Manchester built the first stored-program computer, a pretty important milestone in its own right. Maybe more on that some other time.

There are two notations for Business Processes put forward – BPMN and UML Use Case/Activity Diagrams. My part of the coursework assignment is to apply BPM to the johnlewis.com some processes on the website, for which I’ve chosen Activity Diagrams and Visual Paradigm for UML. I did take a look at the implementations of BPMN, but I found a familiar pattern – they either didn’t work or cost $$$. Fortunately, VP is still serving me well.

The lab session was spent working with my team on the coursework and setting up tasks for the rest of week. As we’re producing a large report and taking different sections, we’ve set up a Google Docs site to drop working drafts onto to help us collaborate. It’s the first time I’ve used Google Docs like this and so far I like it, it’s responsive, intuitive and it’s easy to share a folder with a group of people, so for this kind of work it’s looking good.

In other news, the marks for the Machine Learning module are in and I’m very happy to have passed! That’s two modules, or one-quarter of my MSc done.

Dr. Bishop is a highly respected figure in the Machine Learning discipline and wrote Pattern Recognition and Machine Learning, a great place to start if you’re interested in the subject. It’s certainly on my bookshelf.

He’s giving the lecture in London, Cardiff, Edinburgh and Manchester, and Manchester’s lecture is on the 17th March.

I quite enjoyed having a simple pet problem like this, with a real reason to work through some aspects of it. If you’re interested in having a go yourself, the assignment reminded me of the first pragprog Code Kata – Supermarket Pricing.

As a result of the coursework, I’ve found a UML tool I can live with – Visual Paradigm. I’ll probably do a bit of a review and compare with the other tools I tried soon, but suffice to say it was by some margin the most pleasant and easy-to-use tool of the 5 or 6 I tried. £40 needed to get rid of the invasive watermark, but it looks like when it comes to CASE tools you get what you pay for.

The lectures are proving tricky to keep on top of – the pace is kinda slow (maybe that’s just me), so I find myself struggling to maintain attention. Still, the lecture notes are very detailed, so I spent a a few hours reviewing last week’s notes creating myself some revision material. I’ve been using a piece of software called Freemind to do ‘mind-mapping’, something I found out about in a presentation by Steve Brett in last years’ unsheffield unconference. It seems to work pretty well for the way I do revision, here’s a screenshot if you’ve not seen a mind map before.

So anyway, it’s all good. Coursework part 2 starts now, two more lectures in this module.

New HP dm3-1020ea (centre) versus Dell Vostro (right)

As for the course itself, day two brought in patterns to help understand the problem domain and patterns to help design at a higher level than software implementation, as defined by IBM.

The coursework requirements were also laid out.

15% will be a solution for a set of requirements, resulting in a object-oriented design for an electronics store. To be completed individually, assessment consists of UML Class diagrams in a 4-page report explaining how the classes solve the problems.

35% will be a 4-person team project, analysing a real e-business solution. Assessment will be a 15-page report, and includes team management aspects.

The other 50% will be assessed by exam around June.

First up, the lectures were originally timetabled for a 9:30am start, and are now timetabled for 11:00am. That gives me loads of time between arriving in Manchester at 08:00 and starting lectures to eat, get to the library, do any admin stuff that’s easier when I’m onsite and generally chill out before getting started.

Second – I signed up for ‘IBM Patterns for e-Business Applications’, because I wanted to get some Software Engineering coverage as part of my MSc, and there was some coverage of design patterns in the syllabus for this module in 2009. I was in two minds about it, studying something with ‘IBM’ on it didn’t seem entirely right for an academic course.

To my surprise, the course has been re-branded ‘Pattern-Based Software Development’ overnight, and a complete re-write of the lectures has started to appear that appears to focus on understanding and applying some of the GoF design patterns – pretty much the exact course I wanted to take. I’ve studied and applied some of the GoF patterns before, and I’m really looking forward to learning the syllabus and having my work critically reviewed.

As an aside, it looks like the Manchester CS department is completely re-working its taught MSc Advanced Computer Science proposition, organising the taught modules into ‘pathways’ like Artificial Intelligence and Natural Language Processing. Looks like a good move to me, helpful for students choosing modules.

The lecture material introduced the Strategy, State, Proxy and Item Description patterns. The first three are pretty well known, but it’s the first time I’ve come across the last one.

Coursework material involves UML Class diagrams and designing a system to solve a loosely defined business problem. Unfortunately, it seems that good UML tools are tough to find. After a few days of battling working with the Eclipse project’s UML2 plugin I’ve come to the conclusion that I don’t much like it for simple diagramming. I’ve tried a few other tools with limited success, just a couple left to try. It might be you do have to pay $$$ to get a good one – but we’ll see.

If, after ‘installing’ a plugin for Eclipse 3.4 it’s not visible in Preferences or in context menus, check that your user account has permissions to write into the appropriate Eclipse directories – because Eclipse doesn’t warn you.

Preamble

For those who don’t know, Eclipse is an IDE heavily used for Java development. Like anything else, it’s a delicate balance of awesome and suckage, and today I got caught out by a pinch of suckage.

It’s a plugin-based platform, which means that anyone can write a piece of software that ‘plugs-in’ to Eclipse to extend or enhance the functionality. It’s a great approach, allowing me to tailor my own installation to my needs. Having recently re-installed Ubuntu Linux, earlier today I was trying to set up my plugins without success.

The Problem

I set up the m2eclipse update site as described in the documentation (pretty standard fare… Help > Install New Software…, paste in the update site URL and choose components to install) but after ‘installation’ was completed there was no sign of the plugin. There should have been new options appearing all over Eclipse, but no. Tumbleweed.

Tried installing the next plugin on my list… Subclipse. Same story. So not a problem with a plugin…

The Solution

…and then it dawned on me. I’d installed Eclipse into /opt, which is all locked down to root, with administrative privileges. Schoolboy error – no permissions for the plugin files to actually be installed under the authority of my user account, which is the context that Eclipse normally runs.

A quick chown to root:admin for the /opt/eclipse directory (rather heavy handed – I should probably have worked out which directories I needed write access to, but I was out of patience), ‘uninstalled’ the plugin in the Eclipse, tried the install again and then I was back in business.

I’m really surprised that Eclipse doesn’t complain when it’s ‘installing’ a plugin in directories to which it has no access. I may not be the sharpest tool in the box, but I’m fairly sure that permissions problems happen to other people too. I might go so far as to find out where you feed back to the Eclipse development community for once. Anyways, this post will help remind me next time I get this wrong, it might help someone out, and if nothing else you might be mildly entertained by my ineptitude.

Better for the environment, right? More importantly, I never seem to have a blank CD knocking about when I decide to do an install.

I expected some hassle, but it turns out to be trivial if you’re already on a Ubuntu machine, so long as your BIOS supports booting from USB devices. So…

• Check the computer you want to install into supports booting from USB; if it doesn’t I guess you’re stuck with the CD option
• Slap a USB stick with 2GB space or more in a slot on another Ubuntu machine (make sure there’s nothing on the stick you’ll miss if it gets lost!)
• Start up usb-creator from the command line (just type usb-creator, or sudo apt-get it if it’s not installed)
• Choose the .iso in the usb-creator utility
• Choose the target USB device
• Wait while files are copied and stuff
• Pull out the USB stick when it’s ready, plug it into your target machine and reboot.

The familiar installer screens should start up.

More details here.

My Top Tip for distance learning today has to be: if you have to attend classes, labs, exams – you know, stuff that you can’t really afford to miss, aim to be there an hour early.

Today, I didn’t realise that the exam wasn’t in the same building that I’ve had every lecture, lab and exam so far. In fact, it was on the other side of the campus, and it’s not a small University. I was very glad of having 45 minutes from checking my information to the exam starting! Totally my own fault, of course – focussed on studying and the date and time of the exam, I made an assumption – but these things happen. If you’re there early and everything works out fine you have time to relax and centre yourself. On the other hand, if there is a problem, you’ll be very glad of that time.

The course itself was a fascinating introduction to several aspects of automated learning. Starting out with linear and nonlinear classifiers, moving on to decision trees, then probabilistic classifiers, unsupervised learning and finally sequence learning, we covered a large set of knowledge with significant maths pre-requisites.

Most of the material was quite approachable (now that I’m largely over my irrational fear of mathematical symbols – I wonder if there’s an official phobia for that?), with the notable exception of the probabilistic stuff. I’m not sure why I had such a problem with it and even after some serious digging in books I’m still not totally clear on some of it. More work needed there in the future, I fear.

Funny thing about the maths stuff – it has taken/is taking me a lot of effort to penetrate the notation. Once I can read it, though, the concept hiding underneath tends to be fairly intuitive. Go figure.

So how did the exam go? As with the last one, I can easily imagine how it might have been much tougher. Feels like it went OK, but you never know do you?

Anyway, now the immediate study pressure is off for a few weeks I’m hoping to catch up on some reading (right now, a quarter of the way through Code Complete 2, by Steve McConnell – I’d like to finish that off) and get a few more blog posts in.

I needed to get an measure of the difference in performance between Perl and Java for a simple client application, so I wrote the traditional ‘Hello World’ app in both and ran a bunch of executions averaging over the time from start to end of execution. The net result:

Perl is around 34 times faster than Java.

Really? I thought Java was supposed to be fast? In fact, Dhananjay Nene talked about how comparatively fast a selection of languages – including Java – were on his blog, and cwilbur ’s comments suggest that in that experiment:

Java is around 100 times faster than Perl.

So how can these two conflicting results both be true? I’m sure you’ve already figured it out, but I’m going to tell you anyway.

Java code takes hundreds of milliseconds to start up, because Java code runs in the Java Virtual Machine which needs a little time to get itself ready before your code can run. Once it’s up, however, you can get performance close to (or even better than, in reality) that of typical C++.

On the other hand, Perl doesn’t need that environment and so can start faster but trades off more overhead at runtime, meaning slower running performance.

Just goes to show, application performance is another area where there’s no one right answer – it’s about choosing the right tool for the job – I don’t think there’s any way round these performance characteristics without cheating.