Small Golden Sceptre

Technology, Rambling and Dragons

Posts Tagged Compugeekery

Pogoplug SAN using AoE

Mar 8

Posted by dhenke in Compugeekery | 3 Comments

pogoplugThe Pogoplug E02 is a Linux-capable embedded computer with gigabit Ethernet and USB connectivity. It can be found quite cheap (US$35 or so) on the secondary market. As it was originally sold as a storage appliance for home users, it ships with somewhat inflexible factory firmware. However, it is reasonably easy to replace the bootloader with one which can boot an arbitrary Linux distribution.

Once I got my Pogoplug running Debian, it was surprisingly easy to set it up as network storage using ATA-over-Ethernet. Details after the jump.

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Raspberry Pi, GPS and NTP

Feb 18

Posted by dhenke in Compugeekery | 8 Comments

The Raspberry Pi is an inexpensive ARM7-based single-board computer that runs Linux. Using it, together with an almost-equally-inexpensive  GPS receiver module from Adafruit Industries, I was able to set up a reasonably good NTP server for my home network. While the hardware side was almost ridiculously easy, the software required a bit of effort, including building a custom kernel and building ntpd from sources. Full details after the jump.

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Ubuntu 12.04.1 LTS: Recovering from a Broken libc

Oct 23

Posted by dhenke in Autobiographical, Compugeekery | 17 Comments

Note: Reasonably heavy UNIX-geekery ahead. Mostly Linux-specific, somewhat Debian-specific and a little bit Ubuntu-specific. Skip if that isn’t your cup of ichor.

I recently did something incredibly ill-considered while logged in (as root, natch) to my Ubuntu server box at home. In essence, I told the package manager to uninstall libc.

On a scale from good to bad, this is bad.

Now, I could have booted up from a rescue disk and fixed it. I could have re-installed easily enough (using the trick where you just keep your existing partitions and don’t format them — though this would have inevitably led to some fallout as various config files and customizations got clobbered). Heck, I even had a reasonably recent backup at hand. None of these sounded especially fun, mostly because the machine was in a place where it’s a hassle to stick a head on it. I had three things working in my favor: an open root-privileged shell prompt, Internet connectivity and my native cunning.

Read on after the jump for the full tale.

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Karotz: Movies Application

Aug 22

Posted by dhenke in Compugeekery | No Comments

The Karotz (née Nabaztag) is an Internet-connected embedded system in the form of a stylized mechanical rabbit. I received one of these as a gift, and it’s actually kind of cool. It lacks any kind of display (other than a single multi-color LED), but does have such amenities as a camera, microphone, RFID reader, motorized ears, robust text-to-speech and a Javascript API.

My first application for the Karotz is called Movies. It scrapes the Google movie listings, and reads you upcoming titles and showtimes for the theater of your choice. Full source download and additional discussion after the break.

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Cheap Self-Programming AVR Proto Board

Aug 14

Posted by dhenke in Compugeekery | No Comments

There are lots of proto boards for the AVR microcontroller, and lots of programmers. This post presents my approach, which features easy assembly, off-the-shelf PCB, extremely low parts cost and a built-in USB-based programmer. Circuit, PCB and firmware are all completely Open Source. Read on after the jump for details.

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AVR Dragon: Fixing Bad Fuse Settings

Aug 2

Posted by dhenke in Compugeekery | 5 Comments

This post isn’t about the usual kind of dragon (if there even is a “usual” kind). The AVR Dragon is a gizmo made by Atmel, useful for programming their AVR line of microcontrollers. It’s relatively cheap (around US$50 at the time of this writing) and does many useful things. The specific application I’m going to talk about here is using it to “fix” parts when you’ve set the fuses in such a way that said parts won’t talk to simpler programmers. Details after the jump.

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Netbook Décor

Dec 26

Posted by dhenke in Dragons | No Comments

If this site has a topic at all, then it’s technology and dragons. (It’s right there in the tagline, after all.) Usually I have to make do with one or the other. This is the rare post where I can get both involved. Pictured right is my Acer Aspire One netbook. You might note (“Just look at it!”, etc.) that it has gone from being plain and corporate and boring to being attractively decorated. The process involved a Sharpie permanent marker, and the considerable skill of an artist (not me) who made me swear to conceal his identity, on account of — and I quote — “not being able to draw dragons.”

Much happiness. Your netbook is not as nice as mine. (If you believe otherwise, I want to see pictures.)

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Linux on Zipit

Sep 29

Posted by dhenke in Compugeekery | 10 Comments

Update: Please see my newer Debian on Zipit article for a better installation process.

This is an article about running Linux on the Zipit Z2 instant messaging device. Or rather, it is about running a general-purpose Linux distro, since the device out-of-the-box runs a Linux kernel with proprietary userland software.

Why is this interesting? With a list price of US$50 (and sale prices approaching half that), this device can be an SSH client, DOSbox, NES emulator, video streamer, music player and/or IRC client.

Since the state of documentation seems to be lagging behind the state of development on this device, I’m using this post as an information dump about all the things I found a hassle to figure out (and hope to save others that same hassle).

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I Was Told There Would Be No Math

Sep 28

Posted by dhenke in Compugeekery | No Comments

The so-called “impossible puzzle” (also known as the “sum and product” puzzle) has been kicking around since 1969. It isn’t actually all that hard, but the statement of the puzzle can make it seem intractable when first encountered:

Consider a pair of integers X and Y such that 1 < X < Y and X+Y < 100.
P and S are mathematicians, who know the above constraints and who won’t deliberately lie.

In secret, P is told only the product X*Y and S is told only the sum X+Y.

P: “I can’t find the numbers.”
S: “I knew you couldn’t.”
P: “Then I know the numbers.”
S: “Then I do, too.”

Find X and Y.

Note that there are spoilers after the jump. Please read no further should you wish to attempt a solution on your own.

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Backups on the Home Front

Sep 18

Posted by dhenke in Compugeekery | No Comments

In computing, you have exactly two options: 1) Have current, working, tested backups or 2) don’t care if your data is there tomorrow. There is no third option. Pretending that there is leads only to substantial cussing.

Unfortunately, people mostly either know this already, or won’t be convinced of it until they learn from the school of bitter experience. So, this isn’t a post to try to convince you to take backups; it’s a post about how I do it, presented in the hopes that it’ll make doing so easier and safer. (As with many of my computer-related posts, the actual implementation is somewhat specific to UNIX-like systems, though many of the general principles apply universally.)

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