Monitors and Semaphores in Operating System.

     Now, This is most important topic that might ask during interview session, its better to clear all your doubts before going for interview , I am your friend going to help to clear this concept.

Reasons for using Monitors and Semaphores

      The reason that semaphores and monitors are needed is because multi-threaded applications (like Microsoft Word, Excel, etc) must control how threads access shared resources. This is known as thread synchronization – which is absolutely necessary in a multi-threaded application to ensure that threads work well with each other. If applications do not control the threads then it may result in corruption of data and other problems.

Are we Familiar with this ?

Actually we all use this constraints while implementing synchronization in  multi-threaded Systems.  

Monitors and semaphores are both programming constructs used to accomplish thread synchronization. Whether you use a monitor or a semaphore depends on what your language or system supports.

Now we start with one by one , 

What is a Monitor?

A monitor is a set of multiple routines which are protected by a mutual exclusion lock. None of the routines in the monitor can be executed by a thread until that thread acquires the lock. This means that only ONE thread can execute within the monitor at a time. Any other threads must wait for the thread that’s currently executing to give up control of the lock.

However, a thread can actually suspend itself inside a monitor and then wait for an event to occur. If this happens, then another thread is given the opportunity to enter the monitor. The thread that was suspended will eventually be notified that the event it was waiting for has now occurred, which means it can wake up and reacquire the lock.

What is a Semaphore?

A semaphore is a simpler construct than a monitor because it’s just a lock that protects a shared resource – and not a set of routines like a monitor. The application must acquire the lock before using that shared resource protected by a semaphore.

Example of a Semaphore – a Mutex

Well known example for Semaphore is Mutex.

A mutex is the most basic type of semaphore, and mutex is short for mutual exclusion. In a mutex, only one thread can use the shared resource at a time. If another thread wants to use the shared resource, it must wait for the owning thread to release the lock.

Differences between Monitors and Semaphores

Both Monitors and Semaphores are used for the same purpose – thread synchronization. But, monitors are simpler to use than semaphores because they handle all of the details of lock acquisition and release. An application using semaphores has to release any locks a thread has acquired when the application terminates – this must be done by the application itself. If the application does not do this, then any other thread that needs the shared resource will not be able to proceed.

Another difference when using semaphores is that every routine accessing a shared resource has to explicitly acquire a a lock before using the resource. This can be easily forgotten when coding the routines dealing with multithreading . Monitors, unlike semaphores, automatically acquire the necessary locks.

Is there a cost to using a monitor or semaphore?

Yes, there is a cost associated with using synchronization constructs like monitors and semaphores. And, this cost is the time that is required to get the necessary locks whenever a shared resource is accessed.

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Computer @ Very Low Rates

Low Computer Rates

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Smallest Computer

Ya its right ,,the World Smallest Computer..

Its just like your normal computer and have a great portability.

Comptek has launched UMPC in India, claimed to be the smallest PC in world with all features of a tablet PC including Wi-Fi, Bluetooth and Web camera inbuilt. Weighing only 529 grams, the Wibrain Bl Ultra Mobile Computer is a small (approximately 7.5"x3.25"), Tablet PC with touch screen, mouse pad, 1.2 GHz processor, 1 GB RAM, 60 GB HDD, integrated stereo speakers, USB and 24 Pin connector for external monitor, battery backup and comes loaded with a version of Ubuntu Linux or Wmdows XP.

Long before there were iPod Nanos and laptops, in fact, long before before Bill Gates was even born, a British mathematician proved that it was possible to build computing machines that could be programmed to carry out any calculation that could ever arise. The mathematician was Alan Turing, and the theoretical device he invented in the 1930s is nowadays called a Turing machine. (There is not just one Turing machine; rather they are an entire class of hypothetical computing devices.

The computer built at Bletchley Park, like all computers since, is much more complicated than Turing's theoretical machine. In principle you could build a physical Turing machine, and in fact several people have done so, but they are not useful; it could take tens or hundreds of years to program them to carry out useful calculations, and for some problems even longer to find the answer. They may be simple, but they are not practical. Their importance is that they help us understand what computation is and how it works. (For instance, the security of your credit card number when you order something online depends crucially on mathematics involving Turing machines.)

The idea of building machines to do arithmetic (in particular) is almost as old as mathematics itself. The earliest attempts, such as piles of pebbles or the abacus, were not really carrying out the mathematical computation, they simply provided a convenient way to store numbers for the human operator who actually did the math. Blaise Pascal (1623 - 1662) was one of the first people to design and build a machine that really did carry out calculations, called the Pascaline. Charles Babbage (1791 - 1871) is another famous name in the history of designing calculating machines. But all of the early attempts focused on designing machines to perform particular calculations or particular kinds of calculations. No one thought of building a machine that could carry out any computation.

Part of the reason is that it was not until the 1930s that anyone had tried to specify precisely exactly what is meant by "a computation." Turing invented his "Turing machine" concept in order to provide a precise definition: a function from numbers to numbers (say) is declared to be "computable" if and only if it can be calculated by some Turing machine.

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Victorinox Offers Mission Impossible Secure USB Drives

Victorinox plans to add a secure USB memory stick with Mission Impossible-style features to its Swiss Army knives. The Victorinox Secure devices will have a fingerprint scanner that can detect life, and will self-destruct if the case is cracked. Victorinox is offering $150,000 to anyone who can breach the Victorinox Secure layers of security.

Victorinox intends to add a USB memory stick to its lineup of iconic tools that fold out from the casing of the company's popular Swiss Army knives. The hook that Victorinox announced Friday is that the new products will also sport high-tech security features aimed at preventing the devices from being accessed by others if lost or stolen. "Life is becoming more digital every day, and yet people do so little to protect their data ," said the new product line's designer, Martin Kuster. "The world's most common password is '12345' -- and even encryption can be broken, given time."  

Single-Chip Technology 

The new memory-stick devices from Victorinox will even sport a fingerprint scanner linked to a heat and oxygen sensor capable of determining whether the user's finger is still attached to a living person, the company said. Also on tap is a Mission Impossible-style self-destruct mechanism that will fry the device's internal circuitry in the event that anyone attempts to physically crack the case.

The available memory aboard each USB-enabled knife is expected to range from 8GB to 32GB, depending on the model selected. To prevent Victorinox Secure devices from attracting the attention of airport security workers, road warriors will have the option of detaching the memory drive from the knife's housing when traveling by air.

Victorinox Secure devices integrate single-chip technology that eliminates the need for external and accessible lines between the different coding/security steps, the company said. The data on this chip is also secured through the use of AES256 encryption -- the same 256-bit cypher that the U.S. government has adopted for securing sensitive information .

In addition to the USB drive, the new lineup of Swiss Army knives will include a retractable ballpoint pen, a blade , scissors, a nail file with screwdriver, and a key ring. Frequent fliers in need of the whole kit and caboodle can always place their units in checked baggage.

A Challenge To Hackers 

Victorinox is so confident that its new lineup of secure memory devices is uncrackable that it offered a $150,000 prize last week to anyone who can breach the new product's layers of security protection. Though no one claimed the prize, the jury is still out on whether the product will be adopted wholesale by enterprises.

"It's a cool product that will capture attention," said David Reinsel, group vice president of storage and semiconductor research at IDC. But "adoption en masse by corporations is quite another thing."

There's no doubt that data breaches are expensive for businesses in many ways, Reinsel noted. However, so is data on a computer that sits behind an encryption key that only the employee knows, he said.

"Hence the age-old issue -- corporations (most of them) want to control the encryption methodology and the keys," he said. "Any corporate solution would have to allow for some type of master key so that the company can get at a rogue employee's data."

The new Victorinox Secure devices will initially be launched in the United Kingdom, though Victorinox has yet to unveil a firm release date. Pricing is expected to range between $75 and $270, depending on the amount of memory in each model.

This is great enhance to our PD security and must be use in our day to day life to protect our PD and Data.

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Google Facts and Figure

Google Facts and Figure it Revenue

See the Images carefully

Nokia 888

The technology of Nokia is great .
*design concept
“Form follows you”
A personal mobile communication device which lets you be free and fun. It is light, simple and carefree. You can change its form according to your needs during the day.
*target
It is targeted to the young consumers who are likely to be active and take place in a lot of different activities.
*why this target ?
Because they move and change place too much. They do a lot of different things during the day. So that’s what my design offers : to adjust to the moment, the place and the function.
*technologies that are used
It uses liquid battery, speech recognition, flexible touch screen, touch sensitive body cover which lets it understand and adjust to the environment. It has a simple programmable body mechanism so that it changes forms in different situations.
*the functionality of design
You dont have to carry it in your pocket or on your wrist. You can carry it anywhere, in anyform. You can roll it, bend it, put on your clothes like a clip. It also makes some form changes that makes it more ergonomical: i.e. when you want to talk on the phone, the body form turns into the form of the good old telephone. You can personalize these forms and record them. So it fits you the best in the way that you have chosen. The functions that it has also create a feeling of electronical pet, as it senses your moves, understand what you want, respond you in the best way. It learns you, to fit you better.Also e-motions lets you send forms to the other 888 users. It could be the shape of a heart or a small dance. This way you can talk without words.
*how the user interacts
E-motions… It means electronical motions that 888 has. You can send and receive forms from / to friends. You can send a heart shape to your girlfriend, so her telephone turns into an icon of heart. Or you can send a dancing form to your friends to call them to the party tonight. This is the fun side of the product. If we look from the functionality side, 888 is quite flexible. You can put it into your pocket, roll it and make it smaller, or put on your wrist when you want to make a video call on the go. If you want to talk like a normal telephone, there you have your telephone shape. We go through a lot of places and situations in the daily life, so it seems like one form is not enough.
*what is unique ?
You can change the form of the body. Not just the color. And you can do the same by sending an e-motion to your friend.
*the inspiration
The idea is that “the perfect form” does not exist. “Form follows you”
We create the perfect form for each function.

Nokia Morph Cellphone Rolls Up, Stretches, Cleans Itself

Nokia's new Morph concept phone would use nanotechnology to give it a flexible body with a transparent display that could be re-shaped depending on the user's needs, a far cry from today's solid and chunky devices. Even the electronics inside it would be transparent and flexible, so the whole phone may be twisted and stretched into bracelet shapes or tablet form, and nanotech cleverness means it would even clean itself. Developed in cooperation with Cambridge University, this glimpse of a distant future is now on display at the MoMA in New York. Jump for video and yadda-yadda press release.

hey guys !

See this video its really Interesting..

The technology from Nokia was amazing and its really the great step towards the technology ...

The Life Cycle of Mercedes

This can be the Xtremefun of your life

Mercedes Are very Famous of all Cars

Let us know its History of Sucess......

this all about the History of Mercedes....

Apple releases iPhone software 3.1.3

Lest you think we’re all-iPad all-the-time here, allow us to bring you news about Apple’s last revolutionary device. On Tuesday, the company released iPhone OS 3.1.3, which includes a few minor improvements, security patches, and bug fixes for the iPhone and iPod touch. The update is available via iTunes when you plug in your device.

Among the embarrassment of riches that iPhone OS 3.1.3 brings is better accuracy for the battery level on the iPhone 3GS, a problem where third-party programs would sometimes not launch, and a bug that could cause an application to crash when using the Japanese Kana keyboard.
There are also a few security patches in the release, such as a CoreAudio fix to guard against maliciously crafted MP4 files, an ImageIO patch that similarly protects against malicious crafted TIFF images, improved handling in certain USB control messages to prevent someone with physical access to the phone from accessing private data using the device's recovery mode, and a pair of patches for WebKit that deal with HTML Mail messages and maliciously crafted FTP servers.

As always, Apple’s use of full disk images for iPhone OS updates means you’ll have to download a big ol’ 291MB file.

Broadcom advances 10G Ethernet chips

Broadcom this week unveiled the next generation of its 10 Gigabit Ethernet network interface controller, plus a low-power 10GBase-T PHY.

The new controller can be used in a network interface card, a server LAN-on-motherboard configuration, or a storage adapter. It has two ports on a single chip.

Broadcom touted the chip’s support for simultaneous iSCSI, FCoE and TCP Chimney offload. It also supports Data Center Bridging, PCI-SIG SR-IOV, and embedded virtual bridge for better switching between virtual machines. Plus, it supports the IEEE’s 802.3az Energy Efficient Ethernet spec to save power.

Also along those lines, Broadcom introduced what it is calling the industry’s lowest-power 40nm 10GBase-T physical-layer transceiver. The transceiver is available with either two or four ports, and Broadcom says the technology and power-saving design bring the operating power below 4 watts per port, lower than designs that use 65nm or 90nm technologies. When traffic is light, the chip can drop power usage to less than 2 watts per port. The chip can transmit 10Gbps signals over 100 meters of Category-6A unshielded twisted pair wiring or Category-7 cables.

Coincidentally, Broadcom this week announced its quarterly and annual earnings. The company’s 2009 revenue was $4.49 billion, down 3.6% from 2008. Net income for 2009 was $65.3 million, or 13 cents per share, compared with 41 cents per share in 2008.

Revenue for the fourth quarter was more impressive, a record 1.34 billion, up 19.2% over the revenue in the fourth quarter of 2008. Meanwhile, the income in the quarter was $59.2 million, which means most of the year’s profit was made in the last three months.

Now, computer software that can tell age just by looking at your face

Washington, Oct 29: Women who’re not comfortable revealing their age should stay miles away from University of Illinois-developed computer software that reveals a person’s age just like humans do—by looking at his or her face.

The software, developed at the University of Illinois, Urbana-Champaign, could analyse an image of your face to verify your identity or run a commercial according to your interest.

"Age measurement is very difficult. If you use the face to estimate age we can really get the apparent age, or how old a person looks," Discovery News quoted Thomas Huang, the lead developer, as saying.
For developing the software, the researchers trained their computer algorithm using 1,600 different people with five pictures of each person, for a total of 8,000 images.

The age of the people in the pictures ranged from one year to 93 years old.

While the computer was not told what to look for, it still searched the faces and used its own software to determine which features best determined the person’s apparent age.

One of the features the computer took into account was gray scale— it saw how dark or how light each pixel was compared to other pixels, and then guesses the apparent age of the individual.

"A woman wearing makeup should get a younger age. A smoother skin texture will register as younger-looking," said Huang.

The software also looked at the shape of the face—the relative positions of the eyes, nose, ears, the shape of the mouth, all change over time and can help indicate a person’s age.

"If you use the real age as the ''''ground truth'''', then the accuracy is quite low. But if we estimate [a person’s age] to within 10 years, then the accuracy is about 80 percent," said Huang.

He said that face-recognition software might benefit fast food companies that want to know how many male teenagers buy a particular sandwich or clothing companies that could run a different ad catering to people of all age-groups.

"If you can estimate the gender or the age of the viewer you can change the display. For a younger viewer you might want to display one type of commercial, and show a different commercial for an older viewer," said Huang.

Face-recognition software would also be useful for security. The system could tap into existing security cameras to capture images, which would then be run through the software.

Also, Huang is now upgrading his software so that it could read face images at different angles. In his opinion, his software is just as good as humans at age estimation. (ANI)

Google demos 'Earth' app on new Android OS

At Google's headquarters in Mountain View, Calif., Senior Product Manager Erick Tseng demos Google Earth for Android. The new app mirrors the Google Earth application on the desktop. The app also supports the voice features in Google Earth, searching for geographic locations like

Google Chrome Operating Sytem

Google’s Chrome operating system (OS), which is Linux-based and optimised for web applications, is still a good eight to nine months away from being released.

However, in a media preview of the OS at Google’s local office, I was surprised to learn that the open-source Chrome OS will not be available as a free download. Instead, Google will release the OS with the latest netbooks from major computer (netbook, to be exact) manufacturers, like Dell, HP, Acer or Asus.

Google claims this allows them to give users the best computing experience with the most optimised hardware. In other words, Chrome OS is only free to computer manufacturers but not to consumers.

With the free OS, it gives Google plenty of leverage when dealing with computer manufacturers in dictating the hardware requirements it deems fit for the OS. Manufacturers can further lower the prices of netbooks without having to pay licensing fees for the OS. This, in turn, benefits the consumers. So, what am I complaining about?

Furthermore, given Chrome’s open-source nature, a full working version should be readily available for download by the open-source community once it is launched. But, I don’t think Google is going to bear any responsibility if the downloadable Chrome OS fails on your “unofficial” netbook. And no one will know if such a version will be able to auto-update itself like the official Chrome OS would.