11 February
2007
I am attempting to repair a drive problem in a Powerbook G4 aluminum 15-inch dual-layer SD (superdrive) computer. This is the one with a giant spring-loaded screw on the back to release the battery. On older models like the pismo, the keyboard lifts up easily, and the drive is right under it.
With this model, the hard drive is in the front of the machine and is accessed by removing the whole upper case including the keyboard. This is even worse than the similar operation on a powerbook titanium.
This was assembled by a truly evil mind! To open it, you need to remove tiny screws on the back (about 6), 4 on each side, two small hex screws on on the top near the display, 2 scrws inside the battery compartment, 2 screws inside the memory compartment. (To get the small hex screws out, I had to insert two extra-small slot heads at once to apply enough tension to rotate the screws.)
This is a huge pain and does not seem to be documented elsewhere. All together I count 23 screws, but I might be missing one. After that, to remove the drive you need to remove 3 screws on the tension bar on the right on the drive. They do a low of wiggling and prying.
14 February
2007
Today, February 14th, the International Intellectual Property Alliance complained to the US government about Canadian copyright laws. The first tip that these guys may not be completely even-handed frank is the name of the ogranization, "the International PA" which (according to their own web page was formed "..to represent the U.S. copyright-based industries..." Their desire is to force Canada to come into line with US information control policies. This kind of effort is also being pursued via US pressure with GATT, which has led several countries to adopt regulations similar to the infamous Digital Millenium Copyright Act (DMCA) which goes as far as preventing people from fiddling with the internals of electronic devices (or media) they purchase and own.
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There's more. Read the whole story on "Copyright laws in Canada, GATT and IIPA"
17 February
2007
Nicholas was part of the St. George's School team participating in the CRC Robotics competition called Archemedia 2007. They teams built robots that have to haul 1 foot diameter rings around an arena and stack them up. Their team came in second place overall, as well as doing well in several sub-categories. This includes having a kiosk (booth) that placed in the top 6, for which I believe Nicholas was in charge. This kiosk featured a huge metal dragon (the school emblem) on a pneumatic cylinder that allowed it to go from floor level to about 30 feet in the air. The dragon blew smoke too. The background of the kiosk featured pictures of the team members and biographical information. In addition to a kiosk and a robot, the teams also prepared a journal documenting their activities, a video and a web site.
(click to enlarge)
One of the striking things about the competition is that is has the hype of a college football game. This includes large stands with screaming spectators and plenty of jumping around. Many other schools were involved including a technical school for adults, an assortment of private schools, CEGEPs (junior colleges) and some huge public high schools. Other notable features were a kiosk built by ECS School in which the students dress as mermaids, including having costumes with a single lag, an impressive robot from Laval that could pick up many rings at once (see below), and a kiosm constructed from water bottles. In this latter case, the audience was challenged to guess how many bottles the kiosk was constructed from. [ I guessed 3782, was within 14 of the right answer, and it won me a huge pile of candy. ]
Overall this kind of event is great promotion for science and engineering.
22 February
2007
Due to a flood in our basement, we were forced to do some cleaning up recently. I found an old Next Computer NextStation and a Next Cube. These are attractive old computers that were cited a while beack as one of the "most collectible" tech artifacts from the last millenium. Each of these was made to run NextStep, the UNIX variant that is the predecessor to Apple's OS X, but NextStep is hard to find and exotic. I decided to install a normal UNIX variant to netboot. The Next architecture is supported by NetBSD and the installation and network boot went smoothly except for a few glitches and problems which I am documenting here any other who may do the same
thing. 
For starters, it you netboot using DHCP, as most people will today, then be sure to use full pathnames as the boot names to download. Missing this kind of issues that to a lot of wasted time as the next made successive "RRQ" requests, but was never able to get a file.
The NextCube had no SCSI disk, but recent NetBSD kernels (version 3) seem to expect something on the SCSI bus (at least on my cube, but odds not on my NextStation). This result of the missing SCSI disk is the error message "esp0: SCSI bus reset" which seems to repeat forever. This same problem has been documented on other NetBSD architectures as well. The only solution I found was to recompile a kernel without the esp SCSI driver (which I did not have time to do). If you recompile a kernel on the 68040 25MHz NextStation, it seems to take over 3 hours.
The ROM Monitor can have a password; mine did. To "fix" this, remove the battery from the motherboard for a while (2 to 10 minutes). I also noticed the machine was unresponsive and would not do anything at all without a good battery in place so if your Next Cube or NextStation seems dead and won't even turn on, this could be why.
This blog is based on the Zope product COREBlog. While COREBlog 1.2.5 (and prior) allow an article to be assigned to both primary and secondary when created, the secondary categories are not used in in the blog index, which seems like a clear oversight.
Sascha Welter noticed this, figured out the problem, and fixed it with a patch for an earlier version of COREBlog. That patch isn't quite right for COREBlog 1.2.5, but the trivially modified patch below seems to do the job (see the extended version of this article by clicking the 'permalink' or 'read more' links below).
Note the counts of the number of entries per category will then look wrong, since they only reflect the primary category of each article. Fixing this requires a second patch which I cooked up (see the extended version of this article for details and patches, by clicking the 'permalink' or 'Continue reading' links below).
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There's more. Read the whole story on "COREblog patch for multiple categories"
27 February
2007
March 2nd I'll be giving a talk entitled "Underwater and Amphibious Robotics using Vision-Based Robotic Behavior" at the University of Central Florida. This will be part of the Electrical Engineering and Computer Science colloquium series. My challenge will be to present some of the cool overall system behavior and context, and still get to some of the interesting technical issues such as how we do Markov interpolation in this domain, or how the environment is modeled statistically.
