Reading Bob’s blog entry about lightening over here made me think about lightening and DSL modems. Bob’s quite right about computers most often getting lightening damage through the phone lines not the power lines. The fact that most DSL services use external modems actually provides a extra layer of protection for your computer. For lightening to travel the phone line and damage any of my computers it would have to go through the modem and my Ethernet switch. I’m not an electrical engineer but I suspect this isn’t very likely. Of course it’s still a good idea to unplug your DSL modem during a storm.

I finally broke down and installed some non-open software on my desktop. This is something I try hard not to do. I don’t even have the Macromedia Flash plugin installed. I installed Real player so I could listen to CBC for the election coverage. Hopefully someday CBC will use Icecast so I don’t need this installed anymore.

When working on my Linux QoS project I ran into the confusion over what k,M,G mean in computing again.

Here is the problem. In normal usage k = 1000. Obvious example, kilometer == 1000 meters. However in computing the factor most used is 1024. This means a kilobyte in your computer RAM is 1024 bytes == 2^10 bytes. A megabyte in RAM is 1024 * 1024 == 1048576 bytes == 2^20 bytes. The nice network and hard drive people have decided to use powers of 10 instead of powers of two. This means your 100Mbit network is 100,000,000 bits/sec not 100 * 1024 * 1024 == 104857600 bits/sec. Hard drives are also a fun example of this. A hard drive sold with a capacity of 40 GB can store 40,000,000,000 bits but your computer calculates file sizes with powers of two so this is really 40,000,000,000 / 1024 / 1024 / 1024 == 37.25 GB to your computer.

The networking example is where the problem with Linux QoS came up. The Linux traffic control utilities use a multiplier of 1024 for kbit. My upload data rate is 640kbit. When I specified 640kbit/sec via the Linux QoS utilities I was actually specifying 640 * 1024 == 655360 bits/sec not the actual line rate which is 640,000 bits/sec. Even more fun is calculating download rates from network interface speeds. The network is rated with 10^x but the KB number you see on the screen is 2^x.

Wikipedia has a great article on this whole mess. This article explains the new prefixes that have been introduced to remove this abiguity. So from now on my computer has 512Mib of RAM, the hard drive has 40Gb of capacity and the network interface is 100Mbit/sec.

Nice little summary of WinXP SP2 over at OSNews. It seems MS has a new firewall in this release. What interests me is this screen shot. A simple UI for allowing incoming traffic to listening processes is a great idea. However, I doubt a pop-up window is the best way to handle this. I would guess a lot of users will just hit the OK to make the pop-up window go away. A application that had a list of listening programs and allowed the user to select which ones could receive non-local packets would probably be better. A couple of years ago I started working on something like this for Linux. Unfortunately, like a lot of the play projects I start it didn’t get finished. At least I seem to have had a good idea.