Monday, May 17, 2010

ICQ behind a proxy with pidgin

Using your ICQ account with Pidgin in network behind a HTTP proxy is not a straight forward matter. These are the settings which you should change on your ICQ account settings in Pidgin:
1. Change the Port in the Account|Modify Account|Advanced tab for the server from 5190 to 443.

2. Go to Account|Modify Account|Proxy tab and enter the correct host and port for your HTTP proxy. If the proxy needs an authentication, you should enter your username and password in that tab. Otherwise, leave the username and password blank.

That's it. Hopefully it solves your problem.

Fixing Slackware64 Console Video Mode Bug

I have just finished installing my machine (Athlon64 X2 4000+, 2GB RAM, ATI RS690G motherboard) when I found that the console went blank after logging-out from X. It takes me a couple of hours to figure out what's wrong because the console is just fine prior to starting the X server. After playing around with LILO, I found out that the it's the video mode that causes the bug. My LCD display cannot switch to the requested "default" video mode upon logging out from X. These are the steps to fix the video mode (I'm using LILO bootloader):

1. Edit /etc/lilo.conf and change the video mode to "vga=ask". This will force the dialog that let you choose the correct video mode parameter to pass to the kernel on boot.

2. Reboot the machine.

3. Assuming that you know the correct video mode for your display (resolution and color depth). Enter the correct video mode number when LILO ask for the video mode to be used. LILO will display the video mode supported by the display (acquired via EDID). Anyway, the number corresponding to the video mode is in hexadecimal value. For example, 1280x1024x16 (1280x1024 16-bit) corresponds to video mode number 365h (794 decimal).

4. Edit /etc/lilo.conf and change the video mode to the suitable video mode number. For example, if your display support 1280x1024x16, you should change the "vga=ask" in lilo.conf to "vga=794". In the preceding example, the video mode number in lilo.conf is in decimal.

5. Reboot to see whether you have a flawless console video mode.

That's it. With this, you should be able to fix or enhance the look and feel of your console in Slackware64 (or other Linux distro).

Sunday, May 2, 2010

The Potential of Underclocking

This article from Xbitlabs which describes a detail about AMD Socket AM3 mini-ITX platform highlights the importance of underclocking the CPU in certain circumstances.

I didn't realize the benefits of underclocking previously. However, it's now clear that the reduced power consumption and heat obtained from underclocking opens new opportunity for several constrained systems. For example, for mobility applications and industrial application where the need for ultimate number-crunching capabilities are not the top priority.

One of the mobility application could be a mobile robot with constrained supply of energy with number-crunching need above the Intel Atom territory but could be met by an underclocked Athlon II X2.

In industrial application, it could be a process control board with high enough number-crunching needs but required to be in certain thermal envelope which could not be met by Intel Atom.

Another possibility tempting possibility is underclocking Intel Atom to be used in applications where high performance ARM/MIPS chips do not met the required performance characteristics, or certain x86-tuned code would be more suitable than porting the code to ARM/MIPS architecture.

Well, this is another possible solution that system designers could exploit in certain circumstances.

Adaptive Huffman FGK Algorithm Musing

A short test of the FGK adaptive Huffman algorithm described in J.S. Vitter's paper reveals that the single pass compression algorithm described in the paper ( doesn't update the frequency value in the root of the tree. However, it's not that important because what we need from the tree is only the encoding for every leaf in the tree, i.e. the encoding for the symbols.

The study of various compression algorithm in my spare time mostly motivated by curiosity and the possible use of such a knowledge in future reverse engineering tasks.