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SES, SEO, SEM, Linux and Microcontroller Help, News and Experience sharing Blog
"My PIC Microcontroller Articles are moved to http://picmicrochip.blogspot.com
Posted by shibu V at 11:10 PM
Posted by shibu V at 9:09 PM
On Tuesday, Canonical released a kernel patch to address security issues in the 6.06, 7.04, 7.10 and 8.04 releases of Ubuntu, Edubuntu and Xubuntu. The vulnerability could allow an attacker to execute arbitrary code as root, or crash the system, leading to a denial of service.
"It was discovered that there were multiple NULL-pointed function de-references in the Linux kernel terminal handling code," wrote Ubuntu administrators in the e-mail. "A local attacker could exploit this to execute arbitrary code as root, or crash the system, leading to a denial of service."
The e-mail also detailed a number of other bugs that could be exploited by an attacker who already had some level of access to a computer running Ubuntu.
Posted by shibu V at 12:05 PM
Nehalem is the codename of the new Intel CPU with integrated memory controller that will reach the market next month and that will be called Core i7; this architecture will also be used on CPUs targeted to servers (Xeon) and, a few years from now, it will also be used on entry-level CPUs. CPUs based on this architecture will have an embedded memory controller supporting three DDR3 channels, three cache levels, the return of HyperThreading technology, a new external bus called QuickPath and more.
Based on Intel Core microarchitecture. Two to eight cores. Integrated DDR3 triple-channel memory controller. Individual 256 KB L2 memory caches for each core. 8 MB L3 memory cache. New SSE 4.2 instruction set (seven new instructions). HyperThreading technology. Turbo mode (auto overclocking).
It is important to remember that Core 2 CPUs manufactured under 45-nm technology have extra features compared to the Core 2 CPUs manufactured under 65-nm technology. All these features are present on Nehalem-based CPUs are the most significant ones are:
Posted by shibu V at 10:59 PM
Almost stealthy, AMD has launched four new processors. See them below.
512 KB per core
512 KB per core
512 KB per core
512 KB per core
Posted by shibu V at 10:48 PM
Compare DDR2 and DDR3
Considering the ever growing need of speed and efficiency, understanding Double-Data-Rate (DDR) memory is important to system developers.
DDR memory's primary advantage is the ability to fetch data on both the rising and falling-edge of a clock cycle. DDR1, DDR2, DDR3 memories are powered up with 2.5, 1.8 and 1.5V supply voltage respectively. Temporization is another characteristic of of DDR memories, memory temporization is given in a series of numbers, such as 2-3-2-6-T1, 3-4-4-8 or 2-2-2-5 (CL-tRCD-tRP-tRAS-CMD) for DDR1. These numbers indicate the number of clock pulses that it takes to perform a certain operation- smaller the number faster the memory.
CL - Column Address Strobe, tRCD - Row Access Strobe to CAS delay
Type of DDR Memories
DDR1 with a maximum rated clock of 400MHz and a 64bit(8 bytes) data bus ( Now it is obsolete) .
DDR2 with a maximum rated clock of 800Mhz and a 64bit(8 bytes) data bus. DDR2 memory is physically incompatible ith previous generation of DDR memories.
DDR3 starts where DDR2 left off(800 MHz) and bring the speed up to 1.6 GHz. The 1.5V DDR3 voltage also save power( it will work in 1.36v also)
DDR2 Vs DDR3
DDR2 memories include 400Mhz, 533Mhz, 667Mhz and 800MHz versions, while DDR3 includes 800MHz, 1066Mhz, 1333MHz, and 1666Mhz versions.
Besides the enhanced bandwidth, DDR3 also uses less power than DDR2 by operating on 1.5V(16.3% reduction)
A newly introduced automatic calibration feature for the output data buffer enhances the ability to control the system timing during variations in voltage and temparature.
DDR3 devices introduce an interrupt reset for system flexibility.
Difference in the CL ( Column Address Strobe)
The controller in DDR2 memories works by preloading 4 data bits from the storage are(prefetch) while DD# works by loading 8 bits in advance.
For more details read ECN August 2008, Understanding RAM timings (article) www.hardwaresecrets.com/article/26/1 and powerelectronics.com/mag/power_ddr_memories_require/
If you are doing any kind of PHP development, you'll almost always be using Apache along with it. Here's the way to get PHP up and running on your Ubuntu box.
From a command shell, you will run the following commands:
sudo apt-get install apache2
sudo apt-get install php5
sudo apt-get install libapache2-mod-php5
sudo /etc/init.d/apache2 restart
Your web files will now be found in /var/www/
Posted by shibu V at 7:58 PM
Installing Tomcat 6 on Ubuntu
If you are running Ubuntu and want to use the Tomcat servlet runner, Some times the apt will not work correctly. You can try the following method it will work.
Before you installing Tomcat you must install Java. I would assume if you are trying to install Tomcat you've already installed java, otherwise install Java as per my previous posting. If you aren't sure about your Java installation, you can check with the dpkg command like so:
dpkg --get-selections | grep sun-java
This will give you this output if you already installed java:
Now we'll download and extract Tomcat from the apache site.
tar xvzf apache-tomcat-6.0.18.tar.gz
The best thing to do is move the tomcat folder to a permanent location. I chose /usr/local/tomcat, but you could move it somewhere else if you wanted to.
sudo mv apache-tomcat-6.0.18 /usr/local/tomcat
Tomcat requires setting the JAVA_HOME variable. The best way to do this is to set it in your .bashrc file. You could also edit your startup.sh file if you so chose.
The better method is editing your .bashrc file and adding the bolded line there. You'll have to logout of the shell for the change to take effect.
Add the following line:
At this point you can start tomcat by just executing the startup.sh script in the tomcat/bin folder.
Install rpm files in linux ubuntu hardy
open a terminal windows
sudo apt-get install alien
Use the following command to install your rpm file
sudo alien -i name_of_rpm_file.rpm
You can also convert rpm file to deb file
sudo alien -k name_of_rpm_file.rpm
for install deb file use
sudo dpkg -i name_of_created_deb_file.deb
$ ls -l /proc will give a listing of files inside /proc
A brief walkthrough of the most important files
cmdline - The command line issued when starting the kernel.
cpuinfo - Information about the Central Processing Unit.
dma - Contains information about all DMA channels available, and which driver is using it.
filesystems - Contains short information about every single filesystem that the kernel supports.
interrupts - Gives you a brief listing of all IRQ channels, how many interrupts they have seen and what driver is actually using it.
iomem - A brief file containing all IO memory mappings used by different drivers.
ioports - Contains a brief listing of all IO ports used by different drivers.
kcore - Contains a complete memory dump. Do not cat or anything like that, you may freeze your system. Mainly used to debug the system.
kmsg - Contains messages sent by kernel, is not and should not be readable by users since it may contain vital information. Main usage is to debug the system.
ksyms - This contains the kernel symbol table, which is mainly used to debug the kernel.
loadavg - Gives the load average of the system during the last 1, 5 and 15 minutes.
meminfo - Contains information about memory usage on the system.
modules - Contains information about all currently loaded modules in the kernel.
mounts - Symlink to another file in the /proc filesystem which contains information about all mounted filesystems.
partitions - Contains information about all partitions found on all drives in the system.
pci - Gives tons of hardware information about all PCI devices on the system.
swaps - Contains information about all swap partitions mounted.
uptime - Gives you the uptime of the computer since it was last rebooted in seconds.
version - Gives the exact version string of the kernel currently running, including build date and gcc versions etcetera.
And here is a list of the main directories and what you can expect to find in there:
bus - Contains information about all the buses, hardware-wise, such as USB, PCI and ISA buses.
ide - Contains information about all of the IDE buses on systems that has IDE buses.
net - Some basic information and statistics about the different network systems compiled into the system.
scsi - This directory contains information about SCSI buses on SCSI systems.
sys - Contains lots of variables that may be changed, including the /proc/sys/net/ipv4 which will be deeply discussed in this document.
As you can see, there is literally hundreds of files in the /proc filesystem that may be read and checked for information, and we haven't looked at half of them here.
Posted by shibu V at 10:54 PM
Posted by shibu V at 10:44 PM
Another for apt
sudo apt-get moo will give output like
Posted by shibu V at 8:51 AM
Virtualbox is a powerful virtualization tool in ubuntu hardy
Repository settings are same as my previous post (Java Installation)
sudu apt-get install virtualbox-ose virtualbox-ose-modules
After the installation is finished you’ll need to do just one of the following.
sudo usermod -G vboxusers -a username), and then re-login.
sudo chmod 666 /dev/vboxdrv)
sudo apt-get install build-essential linux-headers-`uname -r`
sudo dpkg -i virtualbox_1.5.6-28266_Ubuntu_hardy_i386.deb
sudo adduser $USER vboxusers)
It is worked in my core2 duo e8200 machine with 2GB RAM and INTEL G33 Motherboard
Linux kernel version 2.6.24-16
Its Great I have created virtual machine with 512 MB RAM and 8 GB hard disk , tested with my Ubuntu hardy live CD , it worked and with out any configuration I have connected to internet and browsed, and also tested open office very fast and no complications.
INSTALLATION OF SUN JAVA 6 IN UBUNTU HARDY
Run System-->>Administration-->>Synaptic Package Manager
(if it ask for passwd enter your sudo passwod)
In Synaptic Package Manager
in ubuntu software tab select first FOUR options
(main, universe, restricted, multiverse)
select Third-party Software tab and
tick first option ( http://archive.canonical.com/ubuntu hardy partner)
and close it
Press reload button
after reloading the list
select search and type sun java
select sun-java6-bin, sun-java6-fonts, sun-java6-jdk, sun-java6-jre,
sun-java6-plugin (don't select sun-java6-doc it will make some problem)
then select apply
To work your browser plugins
Just installing new Java flavours does not change the default Java pointed to by /usr/bin/java. You must explicitly set this:
Run sudo update-java-alternatives -l to see the current configuration and possibilities.
Run sudo update-java-alternatives -s XXXX to set the XXX java version as default. For Sun Java 6 this would be sudo update-java-alternatives -s java-6-sun
Run java -version to ensure that the correct version is being called.
Posted by shibu V at 10:58 PM
A COMPANY CALLED QSTARZ has announced a tiny GPS tracker, which will able to show you where you are and where you’re going. The 60 x 40 x 7 mm BT-Q1300 travel recorder apparently includes the latest GPS chipset MTK with 66-CH. Whose partners want to keep track of them, BAR, PARK, CINIHOUSE .................. My god....
Posted by shibu V at 9:04 PM
The new Solid State Disks (SSD) will replace HDD soon, MICRON has announced two new lines of flash memory solid state drives (SSDs) using high-performance single-level cell (SLC) NAND technology, aimed at enterprise server and notebook PC applications.
SSDs offer performance advantages, power savings and reliability benefits over hard disk drives (HDDs).SSDs perform about ten times faster than HDDs, exhibiting 0.8 ms data access latency compared to average HDD data seek latency of approximately 8 ms.
SSDs consume about one-tenth the electrical power of typical HDDs, running at 0.3 watts when idle and only 2.5 watts while active, whereas HDDs usually draw between 8 to 28 watts. Since they use so little power, SSDs also require virtually no cooling, which also reduces power consumption.
SSDs are also more reliable than HDDs. Using wear-leveling technology, SSDs offer mean time before failure (MTBF) ratings of approximately two million hours compared to typical HDD MTBF ratings of between 300,000 to 500,000 hours.
SSDs for notebook PCs will come in 1.8-inch and 2.5-inch modules with capacities from 16GB to 256GB.
Posted by shibu V at 8:40 PM
Leading hardware Pioneer has developed a technique which will allow optical drives to store 500GB of data. Nikkei Business Daily reported that the technique will use ultraviolet lasers, which emit shorter wavelength rays than blue lasers,
the beam to write data holes in a master disk, each separated by 70 nanometres.
Ultraviolet lasers are a good topic for engineering students seminar
Posted by shibu V at 8:19 PM
ADSL Broadband Internet connection configuration
open a terminal
sudo apt-get install pppoe
sudo apt-get install pppoeconf
if you are not an expert select default and enter username and password when asking
$ pon dsl-provider
Posted by shibu V at 10:11 PM
DOSBOX RUN DOS APPLICATIONS AND GAMES IN UBUNTU LINUX
sudo apt-get install dosbox
(Your can use Synaptic Package Manager and search for dosbox)
After Installation you can make a folder xxxxx in your home directory
(eg: $mkdir mydos)
copy your favorite dos programs and games like Turboc, dave, digger etc in this directory
Now you can run dosbox by typing dosbox in a terminal or
by select it from menu
You will get a small dos window with Z:\> prompt
in Z prompt type the following
Z:\>mount c /home/xxx/mydos
This command for mounting your dos directory to C Drive
(in my case my dos files are in /home/xxx/mydos )
Now You are ready for running your dos programms
Z:\> c: ( change drive to c:)
Z:\>dir (this will list your dos files placed in /home/xxx/mydos)
if ther is our old famous digger game
Z:\>digger and Enjoy it.
Posted by shibu V at 11:25 PM
You can find the list of wireless devices supported by ubuntu
Posted by shibu V at 10:04 PM
ifconfig - lists IP address (similar to ipconfig in Windows)
iwlist scan - scan for wireless networks available in the area
lshw -C network - Shows network interfaces and drivers
route -n - Lists kernel IP routing table -- Good for troubleshooting problems with the internet connection
dmesg | more - Lists boot log -- good for troubleshooting problems with modules/drivers not being loaded
cat /etc/resolv.conf - Lists DNS servers
Posted by shibu V at 8:45 PM
If your wireless card is properly installed use the following command for connect to a wireless access point
sudo ifconfig eth0 down
sudo ifconfig wlan0 down
sudo dhclient -r wlan0
sudo iwconfig wlan0 essid "ESSID_IN_QUOTES"
sudo iwconfig wlan0 mode Managed
sudo ifconfig wlan0 up
sudo dhclient wlan0
Posted by shibu V at 8:39 PM
see the following links
Posted by shibu V at 9:57 AM
You can run graphical utilities like gedit in superuser mode by using
gksu and kdesu commands in command line
Posted by shibu V at 9:46 PM
This will help you to make an iso image of your files and directories
mkisofs -o cd.iso /home/myhome/myfolder
Posted by shibu V at 11:14 PM
This can use for backup your CD/DVD
dd if=/dev/dvd of=dvd.iso # for dvd drives in IDE/ATA
dd if=/dev/cdrom of=cd.iso # for cdrom in IDE/ATA
dd if=/dev/scd0 of=cd.iso # if CD/DVD is scsi/SATA
if your CD/DVD automount , unmount it before running this command that is safer
Posted by shibu V at 11:09 PM
This steps can be done from Windows
Download software Auto Super Grub Disk
Double-click auto_super_grub_disk_1.0 icon, install it, and reboot.
On the next boot, select the UNetbootin-supergrubdisk menu entry; this will launch the Auto Super Grub Disk.
Do nothing till you see your Grub menu again.
Posted by shibu V at 11:01 PM
Disable IPv6 in ubuntu
1. sudo gedit /etc/modprobe.d/aliases
2. Find the line: alias net-pf-10 ipv6
3. Edit this to: alias net-pf-10 off
4. Save the file and reboot
Linux Commands for Shutdown and Reboot
Linux has SEVEN Runlevels( Operating Modes)
init 0 - System Halted
init 1 - Single User Mode
init 2 - Single User Mode with Networking
init 3 - Multi User Mode - Text Mode
init 4 - Not yet Defined
init 5 - Multi User Mode - X Windows
init 6 - Shutdown and Reboot