Category Archives: computing

Detecting Meteors from radio reflections

When I was in school, I remember being told that it was possible to tune an FM radio do a free frequency low in the band and during a meteor storm you could ‘hear’ when meteors struck the atmosphere as the FM signal from distant radio stations would be reflected back down from the ionised meteor trail. This may have been possible as back then there were plenty of high powered FM stations from Eastern Europe using a lower portion of the spectrum and receivers often went below the 88.5 that is the limit on the dial now. But I never heard anything. Over the years as my interest in meteors and radio was peeked I looked into it again, but the number of stations to use was dwindling and there were few artificial sources that could produce an audible ping. Continue reading Detecting Meteors from radio reflections

Updating Solaris 11 zones behind a proxy

I’ve forgotten this several times now so it’s time I wrote a short post to help me remember in future! In Solaris 11 we use the Image Packaging System to maintain the software on the system. This is written in python and uses libcurl and for non zoned systems setting the http_proxy is sufficient to allow the system to communicate with the repo. Continue reading Updating Solaris 11 zones behind a proxy

Old computer magazines free to a good home

I’m clearing out the attic and have some old computer magazines that some of you might be interested in. Free to a good home if you can collect from me, otherwise they go to recycling.

The first batch contains titles like Personal Computer News and Your Computer from around 1981-1983. The second batch are mainly Amiga Shopper (and the odd CU Amiga and Amiga Format) from around 1994.

UPDATE: All gone! Continue reading Old computer magazines free to a good home

Python : generating unittests on the fly

When creating python unit tests you need to create a method in a unittest class. The problem however is when you don’t know until the code is running what these tests will be. In my particular case I need to run a series of tests against a number of Solaris packages. But I won’t know what the packages will be in advance. Continue reading Python : generating unittests on the fly

Python: Searching for a string within a list – List comprehension

The simple way to search for a string in a list is just to use ‘if string in list’. eg:

Continue reading Python: Searching for a string within a list – List comprehension

UK Windows Keyboard on a Mac Book Pro

It started well. I just plugged in the keyboard and it appeared to work. Until I tried typing an email and the ‘to’ line came out with a ” instead of an @. Aha! Simple – just change the keyboard layout.

That’s a lot easier said than done in OSX Lion. For a start there does not appear to be a set of keyboard layouts to choose from.

Enter Ukelele. This tool lets you create custom keyboard layouts. All I actually needed to do was take the Logitech UK International keyboard and remap the | key as everything else was as I needed.

Now I can finally use my old Microsoft Wireless Keyboard 6000 with my Mac.

Tonidoplug Power Supply failure

I’ve been using my tonidoplug as a home NAS server for almost a couple of years now. It’s performed as well as can be expected for 2 mirrored 1.5TB disks attached on a USB hub.

One evening recently though I noticed that it was unreachable. A quick look at the box showed that all was not well, both lights on the network interface were on as was the green light on the box. After trying to reflash the unit I contacted support but they would not replace a nearly 2 year old unit. Though to be fair to them they did offer to sell me a replacement at a discount.

So with the unit dead and no chance of a replacement the ‘void if removed’ sticker was quickly discarded. Here’s the box in its faulted state with the LEDs on:

From experience the most likely thing to die in electronics is the power supply. It clearly isn’t dead here since the lights come on, but a quick check of the outputs with a multimeter showed that what should have been a +5V output was actually +2.5V. Luckily I have a sheevaplug that I use for another home project that uses an equivalent power supply so after a quick swap the Tonido was booting again.

Looking a plug computer forums it appears that there are known issues with some of these power supplies. The Tonidos original power supply was contained in a metal box, as was the original sheevaplug ones that are mentioned in the forums, but my sheevaplug has the circuit board glued to the case with protective black plastic around it. Whether that is to try to reduce the heat build up I can’t say.

Anyway the unit powered back up and the disks and mirror seem to be working fine.

[email protected]:~# cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 sda1[0] sdb1[1]
1465135936 blocks [2/2] [UU]

unused devices:
[email protected]:~#

This does mean that my plans to build a mini-ITX Atom based Solaris ZFS NAS box are now on hold. But at least so are my plans to spend about €500 on it when I can just by a £20 power supply to fix what I have!