FOSDEM geek-fest

Sitting here at FOSDEM, nursing a slight hangover from lots of Belgian beer last night at the Delerium Cafe in Brussels. they reputedly have over 2000 beers on the menu, but that’s still not enough for every one of the 4000+ geeks here to have a different one each!

It’s already been an interesting weekend, and it’s not lunchtime yet on Saturday.
The talk on How a Large-Scale Open Source Project Works is about to begin, so I’ll post this, and update later.

Arduino model railway control

I’ve been playing with a couple of Arduinos for the last week, and doing some physical computing, interfacing with real devices from the microcontroller. It’s been interesting doing some low level electronics again, and it was a great feeling about half an hour ago to have the model railway running under computer control – using the laptop to send commands over the USB port to the Arduino, which then does PWM to control the speed of the train.

There were a few hiccups along the way – not least of which the Arduino crashed repeatedly when the train started moving – it appears that the power pack I was using didn’t like having its load being PWMed, causing voltage problems. I resorted to running the Arduino off the USB supply, disconnecting the common 12V power input to the board, and just using that external power pack to provide power for the direction change relay and output to the loco. Make sure that you keep the ground connected though, as the Darlington TIP120s need that to be common in order to work.

The eventual use for this project is to automate the model layout in the Corris Railway Museum, and allow visitors to put coins in a slot and the train will then run for a number of returns depending on the coin put in. More coins – the train runs a little quicker. The software allows for reed switches at either end of the line for reversing, as well as reed switches for stations.

The hardware driver circuit is shown here in the schematic below (I know it’s pretty rough, but it’s as good as I can do at short notice), and photo of the really dodgy looking breadboard prototype.

The diodes are 1N4004s and the caps are 0.1μF to protect against reverse current from the inductive loads.

MRCC1Breadboard MRCC1

Computer Errors – in Haiku

Three things are certain:
Death, taxes, and lost data.
Guess which has occurred.

Everything is gone;
Your life’s work has been destroyed.
Squeeze trigger (yes/no)?

Windows NT crashed.
I am the Blue Screen of Death.
No one hears your screams.

Seeing my great fault
Through darkening blue windows
I begin again

The code was willing,
It considered your request,
But the chips were weak.

Printer not ready.
Could be a fatal error.
Have a pen handy?

A file that big?
It might be very useful.
But now it is gone.

Errors have occurred.
We won’t tell you where or why.
Lazy programmers.

Server’s poor response
Not quick enough for browser.
Timed out, plum blossom.

Chaos reigns within.
Reflect, repent, and reboot.
Order shall return.

Login incorrect.
Only perfect spellers may
enter this system.

This site has been moved.
We’d tell you where, but then we’d
have to delete you.

Wind catches lily
Scatt’ring petals to the wind:
Segmentation fault

ABORTED effort:
Close all that you have.
You ask way too much.

First snow, then silence.
This thousand dollar screen dies
so beautifully.

With searching comes loss
and the presence of absence:
“My Novel” not found.

The Tao that is seen
Is not the true Tao, until
You bring fresh toner.

The Web site you seek
cannot be located but
endless others exist

Stay the patient course
Of little worth is your ire
The network is down

A crash reduces
your expensive computer
to a simple stone.

There is a chasm
of carbon and silicon
the software can’t bridge

Yesterday it worked
Today it is not working
Windows is like that

To have no errors
Would be life without meaning
No struggle, no joy

You step in the stream,
but the water has moved on.
This page is not here.

No keyboard present
Hit F1 to continue
Zen engineering?

Hal, open the file
Hal, open the damn file, Hal
open the, please Hal

Out of memory.
We wish to hold the whole sky,
But we never will.

Having been erased,
The document you’re seeking
Must now be retyped.

The ten thousand things
How long do any persist?
Netscape, too, has gone.

Rather than a beep
Or a rude error message,
These words: “File not found.”

Serious error.
All shortcuts have disappeared
Screen. Mind. Both are blank.

Program aborting:
Close all that you have worked on.
You ask far too much.

Your file was so big.
It might be very useful.
But now it is gone.

Chip and pin just as fallible as old system?

A Guardian article about how chip and pin is not really any more secure than the old system, and the only change is that banks are now not paying claims, instead blaming the card owner for giving their cards and pins out. Their argument – you can’t copy these chips!

The article raises some important security concerns. Also, do you believe that reported card crime is down, now that you don’t report it to the police, the bank does that for you after they decide if it’s worth reporting?

And rather than make another post, I just have to link to this article about airport and airline security, and how completely absurd the whole thing is.
Personally, I fell that they’ve already won, by getting us to allow our government to take away civil liberties, whilst most of the voting public either encourage it, or just lay down and take it.
One of the comments near the top of the page, made by a pilot who is also subject to these security checks puts it quite succinctly:

Let’s think about something. I am in my pilot uniform and going through security and about to fly an aircraft and passengers from point A to B. I and my co-pilot will be sealed in the cockpit in front of a security door that cannot be opened from the outside. I will have in my hands the only “lethal” weapon used on 9/11, – the control yoke. So just what is it the TSA is checking me for? A gun? A knife? What? If I had been recuited by ‘the bad guys’ do I need to carry ANYTHING lethal? Of course not! Therefore, I should not have to go through security at all!

Stop telling me about

Please people, stop telling me that (or bu_tnoo7) is a hacker and I shouldn’t add him to my facebook account.

It’s already wasted far too much bandwidth, the message itself that is forwarded is technically rubbish, and you yourself are being used by the “virus” as the propagation mechanism.

Oh, and before I get a load of comments on “how do you know”, “what makes you an expert” – I teach a course on hacking to the Masters courses, and if you don’t believe me, then do some research yourself –


If you receive this or a similar message, please do not forward it to your friends and colleagues. Forwarding unsolicited chain letters wastes time and bandwidth.

Grr grr grrr

Hmm, where does this start…

My fileserver used to run Ubuntu Dapper Drake Server.

I was trying out icecast to send a music stream to all the Xboxes and other machines in the house… so I installed a few packages to try and do that, and found that I really ought to be updating the system. Lets upgrade to Feisty Fawn thought I, and having done an dist-upgrade in the past without a problem thought that it’d be straightforward. How wrong could I be?

Alter sources.list, apt-get update, deep breath – apt-get dist-upgrade…

Something breaks – it’s complaining about /usr/X11R6/bin not being a symlink – please fix and try again… odd

Ok I try changing it into a symbolic link, and try again, fails again, differently, now complaining that rdesktop has a clash with something else…

After fighting with it for a couple of hours, I give up – the installation process has completely borked the underlying installation, and the system won’t even boot now.

Booting off a live CD at least allows me to back up /etc onto one of the other spindles – at least I won’t lose all my configuration even if it all goes titsup.

Now I look around and find that I’ve got a Feisty install CD, so I pop that in, and it seems to go ok – I install over the top of the old installation – yes it moans that something might get broken, but I’m willling to take the chance before re-formatting the disk. It appears to go ok, but when I come to boot – nada, well, not quite it reports “Cannot write to disk”. Is my hard disk dead? After about half an hour of chasing false leads about dual boot systems, it appears that there is a problem in the Grub menu. The last line has “savedefault” on it. Now my guess is that it’s trying to save to the hard disk, but as that was mounted read-only, it failed to write anything and stopped booting. Comment out that line and things progress normally again.

Of course, I had to change out the hard disk first as I thought that the drive might be on the way out (it was a 10 year old 4.3G drive)

Once I had done a clean install, at least the system booted, and I’ve got my /home disk mounted in the right place, but now my RAID card doesn’t want to start:

dmesg relevant lines:
pata_sil680 0000:00:09.0: version 0.4.6
PCI: Unable to reserve I/O region #1:8@de00 for device 0000:00:09.0
pata_sil680: probe of 0000:00:09.0 failed with error -16

lspci relevant lines:
00:09.0 RAID bus controller: Silicon Image, Inc. PCI0680 Ultra ATA-133 Host Controller (rev 02)
Subsystem: Silicon Image, Inc. Winic W-680 (Silicon Image 680 based)
Flags: bus master, medium devsel, latency 32, IRQ 11
I/O ports at de00 [size=8]
I/O ports at dc00 [size=4]
I/O ports at da00 [size=8]
I/O ports at d800 [size=4]
I/O ports at d600 [size=16]
Memory at efffff00 (32-bit, non-prefetchable) [size=256]
Expansion ROM at eff00000 [disabled] [size=512K]

lsmod reports:
pata_sil680 10884 0

I tried all the standard things of turning off acpi and PnP stuff at boot and in the bios, and still no joy – I finally gave up at gone midnight.

So currently I’m stuck with the file server not able to access four of it’s drives (over a Terabyte of storage) until I work out why I can’t access the raid card.
Of course it’s probably going to come down to reflashing the BIOS on the motherboard, so I’ll probably look into that tonight.

Grr grr grrr

Laptop for Lowri – update

Well, I met Lowri over lunch at The Anchor Inn, Oldbury-on-Severn. In about a week, Lowri is off on the Four Borders Expedition, which is the British Universities Kayak Expedition 2007.
A couple of months ago, I had a desperate plea from Lowri, informing me that she’d killed her laptop, and was going to need one for the expedition… could I find a way to provide one.

So last weekend I finally was able to deliver a refurbished Panasonic Toughbook CF-28, which I bought from Icex. When I first asked my Head of Department if he could provide money for a machine – he said no, as he thought it was going to be fairly expensive, but after I did some desperate searching around, I found this one at a price which he could afford.

Hopefully, she’ll find it difficult to destroy this machine, and we’ll get some really good reports back about this once-in-a-lifetime trip.

Best of luck Lowri, and come back in one piece.

What does Physics teach you about the construction of the dermis?

Apparently, according to the AQA examination board, you should learn about the dead outer layers of skin protecting the living layers underneath, in order to answer the question on a GCSE Physics examination paper.

There’s a story on The Register about this here – be sure to read the comments, there’s an especially good one suggesting answers to the mentioned questions.

Wellington Grey’s Open Letter

And we wonder why we’re having to do so much remedial teaching to our first year entrants.

How has the user experience changed in 20 years?

Reading Risks Digest this morning I came across a link to an article comparing a 1986 Mac Plus and a 2007 AMD Dual core. The question posed was how has the massive increase in computing power has changed the speed at which the most commonly performed tasks are performed.

“The most amazing achievement of the computer software industry is its continuing cancellation of the steady and staggering gains made by the computer hardware industry…”– Henry Petroski

Of course, some of you might already have guessed the outcome, and some might not agree with the tests as presented, but the fact is that the tests actually look pretty fair when you consider what most office workers do with their PCs.

Anyway you can read the article for yourself here on hubpages