How To Test The RAM On Your Computer

The RAM is arguably the most important part of your computer. Apart from the processor, of course, but without some kind of memory, even the process is pretty much useless. A computer, without RAM, cannot run any application that you tell it to and might as well be a dead paper weight.

If you’ve noticed unusual freezes and random operating system/application crashes on your computer, the RAM should be your first line of diagnosis. The RAM on a modern computer is composed of millions of cells that store the data for the computer to process and failure of even a single cell can cause weird errors that can be extremely difficult to diagnose.

Memtest is an open source utility that verifies the RAM installed on your computer for any defects. Since, this is an open source tool, there are versions available for practically every operating system and I’m going to use the Mac OS X version of memtest today since that is what I’m most familiar with. You should be able to use the same command line switches with the version of memtest available for your operating system.

Download MemTest For Free

Memtest is available as a free download so just download it to your computer and unzip the file. You should now have a .pkg installer that you can just double click to install memtest. This installer does nothing other than installing the memtest binary to /usr/bin.

To start testing the RAM on your computer, launch Terminal.app and execute memtest.

Sharninders-iMac:~ sharninder$ memtest all 1

The above command will make memtest run through it’s complete test suite once. In general, it is better to test at least twice, or even let it run for a few hours if you want to be completely sure. If you don’t specify any number after the “all”, memtest runs indefinitely and will have to be stopped by pressing the ctrl+c key combination manually.

If Memtest throws up an error or memtest itself freezes, you’ll know for sure that the RAM is bad. If not, well, time to start diagnosing other parts of the computer.

Memtest for PCs

If you’re not running a Mac, you can still use memtest to diagnose the RAM of your PC, though the process is a little different. For PCs, memtest is distributed as images that you can burn onto CDs or USB flash drives.

Download one of the many pre-built images and burn it to a CD or to a USB flash drive, depending on the image. Now, shutdown your computer and reboot it using the CD/USB Key that you just burned. That should start Memtest straight away. Let the diagnostics run for a while or till you’re sure that the RAM has been tested thoroughly.

Have you ever had the RAM in your computer go bad ? How did you diagnose it ?

 

HowTo install RockBox on your iPod

Apple’s iPod music player is the most popular music player on the planet. The iPod along with the iTunes store has revolutionized not only the music industry but also the complete music distribution business. It is this music business that has brought back Apple, the company, from the brink of bankruptcy and made it into the household name that it is today.

Even though there are many fans of the iPod’s simple and clean interface, there are many who would like their iPods to do still more. And for them the RockBox open source project brings hope.

RockBox is an alternative open source firmware for a lot of different music players including Apple’s iPod and today we’ll show you how you can also install RockBox on your iPod and make it do much more than what Apple ever intended.

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Elisa – Open Source Cross platform Media center

Elisa media center Ellisa is an open source media center that can play DVDs, VCDs, video files and even display your photos. The support for video files is extensive and the player can handle almost any video that you might throw at it.

Elisa is extensible and is based on a very neat plugin architecture, which means that if there are features that you miss from the default install, they’re usually just a plugin away.

In the true spirit of open source, Elisa is available for both Linux and Windows with a Mac OS X port on the way.

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Play Space Invaders in Openoffice Calc

OpenOffice LogoWho said open source developers were a boring bunch of people. I’m quite sure that person hasn’t met the developers of Calc.

For those of you who’ve been living under a rock until now, Calc is the Spreadsheet part of the OpenOffice.org suite and today we are going to unearth a very cool easter egg game programmed within Calc by the developers.

Open a Calc Spreadsheet and type =GAME(“StarWars”) into any cell. The text should be typed exactly as written.

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How To Recover data from an iPhone backup

My sister lost her iPhone a couple of days back and with that all her contacts, notes and calender entries that she had painstakingly stored on the device.

iphone

Her only hope of getting all that important data back was the backup that she had taken a couple of days earlier and she asked me to help her out.

This was my first time dealing with an iPhone backup and I didn’t know where to get started trying to recover data from the backup.

Well, truth be told. The iPhone is not the most open among gadgets. And it isn’t easy to get your data off it. Apple has tried it’s best to hide any iPhone related information from the user’s view. And they have succeeded to an extent, atleast the primary consumers of Apple’s goods don’t really care where (or more importantly, how) the data is stored, as long as Apple provides an application to access it.

In the iPhone’s case, the application is iTunes and the only way to put this data back on to the device is to use iTunes … unless you know where to look for it.

On a computer running windows vista, the data backup is stored in the following location:

C:\Documents and Settings\USERNAME\Application Data\Apple Computer\MobileSync\Backup

Under the backup directory, you will see a directory which looks like a unique ID. This is the directory in which the backup is created, everytime you backup your iPhone using iTunes.

In this directory, you will see a number of files with the *.mdbackup extension.

The .mdbackup files are the actual backups of all the applications and settings of your iPhone. So, the first thing you should be doing is, make a backup of these files :-)

If you use an editor to view these files right now, all you’ll see is garbage, cause these are not text files. They are what Apple calls Binary plists. And to decrypt them, you ideally need a Mac and this utility.

I used the command line version of the utility since I only had console access to a mac and that worked for me.

I first copied all the *.mdbackup files, that I had collected from the iTunes backup folder, to the Mac and ran the following command to zero in on the files that actually had any useful data. I was the most interested in the Contacts data, so that’s what I searched for first.

grep ‘AddressBook’ *.mdbackup

AddressBook is the name of the application which stores, well, address book data on an iPhone. It is only named Contacts in the interface. The actual application name is AddressBook and when I searched for that string in the backup files, I got three files as a result.

I opened the first file using a text editor and it turned out to be the one I was interested in. The word AddressBook is in the beginning of this binary file and it also mentions the database name, where all the data is stored. Yay !

iphone backup

So, now to get to that data base file, we need to use the decoding utility that we downloaded earlier.

decode iphone

So, we’ve got our database file. The decode iphone utility will put it in the following folder structure

/Users/<username>/MobileSyncExport/Library/AddressBook/

Open the database with the following command:

sqlite3 AddressBook.sqlite

and you’ll be dropped to the sqlite prompt. At this point, you need to understand the schema of this database a bit before you can proceed further. Give “.tables” command and you should see the following output.

iphone backup database tables

At this point, I had to use a bit of trial and error to figure out which table holds what data. To view the schema of a particular table you can use the following command.

.schema <table name>

Using this command on the ABPerson table gave me the following result.

iphone schema

There was other information also, but this is basically what I was interested in. So, this particular table was all the information about the a Person, except the phone number. To look for the phone number, I had to look at another table – ABMultiValue. And the two tables are linked through the ROWID and record_id fields in the ABPerson and ABMultiValue tables respectively.

It turns out that the ABMultiValue tables lists all the phone numbers and a quick “select * from ABMultiValue” gave me the answer I was looking for. So, now I finally know where all the data is. To collect all the data in a single place, I used the following SQL query.

select ABPerson.first,ABPerson.last,ABMultiValue.value from ABPerson,ABMultiValue where ABMultiValue.record_id=ABPerson.ROWID

Once I’d confirmed that this was indeed the correct data, I gave the following command on the sqlite prompt

.output backup.txt

That made sqlite put all output into the backup.txt text file rather than the console. And I was set. Ran the above select statement once again and I had all the phone numbers in a nice text file.

How was that for a weekend project, eh ?

In a future post, we’ll talk about taking out the notes and Calender entries from a backup file. The procedure is almost the same, so if you guys can figure it out yourself till then, post the solution in the comments.

Convert videos for your iPhone with free tools

ffmpegThe iPhone is a wonderful device to watch videos thanks to it’s big and bright screen. The only problem I have with it is the limited number of video formats that it supports.

Most videos that I download from the net are in formats that the iPhone refuses to understand and play. I’ve tried searching online for utilities to convert videos for the iPhone, but it looks like almost all software available for this purpose online is either free or doesn’t do a good job. While freeware is almost non-existant (or of bad quality), a lot of shareware that is available insist on acting nasty and adding watermarks and other DRM to my videos.

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