Long-term Memory

I’m again having problems with my new MacBook Pro (the late 2008 unibody one). The problem is most easily visible when BootCamping into Windows and running whatever 3D application (I use 3DMark06). Within 5 minutes, the machine crashes. After some trail-and-error, I found out that it appears to be a thermal problem.

Normally, when the load goes up, the fans kick in to keep the temperature down. Mine don’t… When stressing my CPU under MacOS, it happily goes up to 90ºC with the fans still idling at their standard 2000rpm. Needless to say, a bit of GPU-load increases the temperature beyond the safety-thresholds.

Resetting the SMC solves this problem only partially. On the first boot with a clean SMC, the same CPU-test brings the CPU to 70ºC with fans blazing at 4750rpm, as it should be. Once the machine goes through a sleep-wake cycle, the same test brings it straight up to 90ºC.

Just when I was about to call Apple Care, a software update pops in: SMC Firmware Update 1.2, looked promising, but the problem persisted… I’ll call Apple Care tomorrow.

Continue reading ‘Cooling problem with MacBook Pro’ »

Place: Sporthall Braillard, Ruisbroek
Flights: 2
Time flown: 0h19 (cumulative model timer: 2h56)
Heli battery recharged with: (1) 1639 mAh; (2) balanced 1896 mAh;
Tx battery recharged with: not recharged

Comments:
Indoor flying. The tail vibrations mentioned earlier are probably caused by some slop in the linkage. I tried various gyro-gain settings and the vibrations did not seem to be affected.

Since PhotoShop is a bit too expensive, I’m sticking to The GIMP. When trying to get The GIMP to work under MacOSX (Leopard) I had two issues. The first one was a huge lag in the mouse pointer. Apparently this was caused by a specific version of X11. Since I’ve updated to 10.5.6, the problem disapeared by itself.

A second issue I was having is that (by default) the first mouse-click simply activates the window. The GIMP uses multiple windows, making this very anoying: to switch to another tool, I had to click twice. This blogpost gives the solution:

$ defaults write org.x.X11 wm_click_through -bool true

Recently I got a PowerBall. Needless to say, I wanted to know exactly how this thing works. Although the Wikipedia article gives some descritption, I found this post on Usenet (local copy) that goes into the dirty details of formulla’s.

In my home setup, the Wireless LAN and the Wired LAN are on different subnets. The communication between the two is fully routed, so from the IP point of view, this works perfectly. Most protocols just use DNS and just work. There are, off course, some exceptions to this rule that needs special treatment. One example is, big surprise, Microsoft’s name resolution which works by using broadcasts. Since routers don’t forward broadcasts, you need a trick to get this to work across subnet boundaries: a WINS server.

Another example is Apple’s Bonjour protocol (aka Zeroconf aka Avahi aka Rendezvous). The technical details are a bit different (multicasted instead of broadcasted; based on DNS instead of proprietary protocols), but the result is the same: it doesn’t work across subnet boundaries. Obviously, this protocol is extended to work over a Wide Area Network (WAN), but for some reason, Apple decided that iTunes (and iChat) only supports local Bonjour. (It won’t surprise me if the RIAA has something to do with this.)

Continue reading ‘Sharing iTunes across subnet boundaries’ »

One of the things to pay attention to when building any RC vehicle is the setup of the servo’s. In (almost) all cases, the servo is connected to the controlled handle using linkages. One of the rules-of-thumb is that the servo, connecting rod and slave handle need to be at right (orthogonal) angles. Obviously I wanted to know WHY. John Vugts explains this in more detail, but I still wasn’t satisfied.

So I went through the math and ended up with a calculator to draw the curves on-demand. It’s a standalone JavaScript calculator, so it can be used offline. It uses Open Flash Chart to draw the graph.

Note that the angles are measured in the mathematical way: counterclockwise starting from the horizontal X-axis.

Recently I was troubleshooting a networking problem from my work, Windows notebook: an FTP server behind a firewall was not reachable. FTP is known to be a tricky protocol to get through firewalls (it opens a second connection on random ports), so I went straight into troubleshooting bottom up.

First step is to verify the control-connection. I usually test this by manually connecting to port 21 using netcat (or telnet). netcat reports that the connection is open, but shows no server-header. Normally one would assume that the firewall allows the connection, but there is something wrong with the FTP server. If only it would be that easy…

Continue reading ‘Windows lies about open ports’ »

Place: Sporthall Braillard, Ruisbroek
Flights: 3
Time flown: 0h27 (cumulative model timer: 2h37)
Heli battery recharged with: (1) 1566 mAh; (2) 1844 mAh; (1) 1774 mAh
Tx battery recharged with: 607 mAh
Starter battery recharged with: 1187 mAh

Comments:
Indoor flying. Finally got the chance to properly trim my miniTitan. The gyro still needs some tuning: when I stop the rudder command, the tail overshoots, then comes back. Also sometimes I notice the tail vibrating left-right at around 3Hz. Unsure if this is a gyro problem or just a vibration problem.

I tried recharging my LiPo with the starter battery, but after 15′ (680mAh) of delivering 2.5A the charger reported that the source battery was too low… Luckily one of my friends had some spare 12V power.

On the third flight I tried getting some forward speed. Even though it was a big indoor hall, this machine wants more…

My car has a CD player build-in that supports MP3 CDs. However, it’s fairly picky on the format of the disc. I tried to burn a CD using Burn Folder which comes with Leopard, which creates a multistandard disc containing a HFS+, an ISO-9660 with Rock Ridge, and a Joliet with Rock Ridge. While this looks very nice on paper, the car’s CD player was less satisfied: “Error CD”.

Another issue is that the player has no support for M3U-playlists. It does, however, support “albums” (directories), which can be used to emulate playlists. Just add a number prefix to each filename and it’ll work. Placing the same file in multiple playlists/albums/directories is possible, but wastes space. But this can be worked around.

Continue reading ‘Faking playlists on an MP3 CD’ »

Time Machine is the Mac way of doing backups. The concept is fairly similar to incremental rsync snapshots. Officially, Apple does not support Time Machine backups to a network volume: network drives don’t show up in the Time Machine user interface. The only way to get network-based Time Machine is by buying a Time Capsule.

When doing a Time Machine backup to a normal disk (I tried it with a LaCie 1TB USB disk), one can see the file structure created. Mine looked like this: Backups.backupdb///Macintosh HD/… Inside this directory is my full system (minus the parts I explicitly excluded in the Time Machine config).

Since we have more than 1 Mac, I’d like to have all of them back up to the same hard drive. I already have a Linux-based server serving files over AFP. This is where it gets more interesting…

Continue reading ‘Time Machine to a linux server’ »