Alan Turing and Colossus

Today , I shall dedicate this article to the father of Computer Science , Alan Turing . Let us begin on a funny note. As a legend goes , it is said that Alan Turing entered into the field , after having suffered a loss in his love life.

One of the most crucial achievements of Sir.Alan Turing , was the deciphering of the Enigma code , of the Germans , which helped , in saving millions of innocent lives , during the  second world war.

Let us  learn about the ENIGMA , before proceeding to the  " Colossus " , which broke the ultimate code .


Quoted : 
"During the 1920s, the Germans created the "Enigma code" machine, which led them to believe that their coded messages concerning military and other top secret operations were beyond being decoded. The machine, which resembled a typewriter, was capable of doing millions of calculations in milliseconds, and the secret codes that controlled them were regularly changed everyday."

Ref for image : 1)http://www.wired.com/images_blogs/gadgetlab/2009/05/enigma-8-rotors-1000pxjpg1.jpeg

                             2) http://www.instablogsimages.com/images/2007/07/19/enigma-machine-ebay_48.jpg

Let us now proceed , to the Colossus :


Quoted : 
"Turing undertook the construction work of a special-purpose electronic machine all the way. In January 1943, he headed up a team of scientists whose specific goal was to try to break Enigma code. To do so, the team developed a computer – called the "Colossus" comprising 1,500 vacuum tubes."


Some pictures :

Ref for images : 1)http://www.clemson.edu/caah/history/FacultyPages/PamMack/lec122/coloss.jpg
                              2) http://www.costablancahotmale.com/images/stories/ColossusX.jpg



Reference :  Colossus Computer and Alan Turing: Machine that Broke the Enigma Code and the Cryptographer Behind it http://computeraccessories.suite101.com/article.cfm/colossus_computer_and_alan_turing#ixzz0j7g3RNp2

Posted By :
Jayanthi GM(Course Instructor Java,PESIT)
Prashanth Raghu (Student Assistant)

R-Trees and it's significance in Spatial Databases

R-trees , are a variant of B-trees which are extremely efficient , for spatial databases , as their structure and oraganisation , greatly has a lot of implied order and spatial relations.

R-trees , are also called as MBR trees( Minimum Bounded Rectangle ) .  Their way of indexing and searching mechanisms , greatly resemble with that of B-Trees , wherein , we start at the root node and proceed to the leaf node , which contains the actual node information. In R-Trees , the search begins , at the periphery of the outermost rectangle. The search proceeds to the rectangle , which bounds the rectangle , to be searched at the next level , until the rectangle is actually found.

Insertion , always occurs at the node , which has the least number of nodes. If their exists a conflict , the node is added at the node , which contains the minimum area .

IBM ' s Informix database , uses R-tree in it's indexing mechanism.

For a complete overview,
Visit : http://en.wikipedia.org/wiki/R-tree
For a simple demonstration,
Visit: http://gis.umb.no/gis/applets/rtree2/jdk1.1/

Posted By,
Jayanthi GM (Course Instructor Java , PESIT)
Prashanth Raghu ( Student Assistant)

Live Locks

A livelock is similar to a deadlock, except that the states of the processes involved in the livelock constantly change with regard to one another, none progressing. Livelock is a special case of resource starvation; the general definition only states that a specific process is not progressing.

A real-world example of livelock occurs when two people meet in a narrow corridor, and each tries to be polite by moving aside to let the other pass, but they end up swaying from side to side without making any progress because they both repeatedly move the same way at the same time.

Livelock is a risk with some algorithms that detect and recover from deadlock. If more than one process takes action, the deadlock detection algorithm can repeatedly trigger. This can be avoided by ensuring that only one process (chosen randomly or by priority) takes action.

Posted By,

Jayanthi GM (Course Instructor Java , PESIT)

Prashanth Raghu (Student Assistant)

Importance of POSIX Standards

It is common for us to complain about the POSIX standards which we are made to mug up at the UG level . But ,this apart we need to understand the importance of such standards . Really very interesting application . I shall avoid going into the technical details and provide the link to the application .

http://www.mil-embedded.com/articles/id/?3093