I have been working in TCS from past 5 years. Here, I am writing the process that I came across to be selected.
It was an Open Interview for all college students of Gujarat. We gathered at 10 AM. After some announcements & PIN number distribution, we are ordered to go to our Computer Lab for written exam.

Written Exam: 
There were 35 Aptitude Questions with 0.33 % negative marking for each wrong answer. TCS supervisors, themselves informed us not to attempt all 35 questions. And if attempted, then they provided assurance that we might get 0!!! And also I knew that my fear of weather being selected or not, would never allow me to attempt all. Starting questions were too long. But, fortunately I found the pattern of question. All questions were only of last two lines.
In between, I reached third last question:
The number of which half are 5 more than 1/6:   1. 10       2. 8          3. 12          4. 15

Calculators were allowed to be used. So, on the exam time, you become to solve easy
question using Calculators!!! I found answer, I went to exam screen & seen the
dialog box: "Time’s up!" I had just 20 questions attempted.

Later, after lunch, I came to know about clearance of written exam from my HR in her office. I filled one information form of TCS. And we are assigned interview panel.

Technical Round: 
It was Jay's turn. Jay was form VVP. We both were also together in Argusoft, Gandhinagar. His technical interview took around 40 minutes. I was waiting outside for my turn as I was from the same panel. When it was my turn, I was made free of tension against interviewers. They took it really very frankly. I was asked about my subjective interest, question of my subjects of study (Operating System, Networking etc.), technical computer & hardware related question, my field of interest and Java questions.
This interview was very interactive. We were talking with each other freely enough like
clarifying the concepts! Finally, I was told to go for the next round of interview i.e. Management Round that I was facing first time.

Management Round: I thought it to be HR interview only. But, it was not. I was asked about latest situation of
IT, cloud computing. I was asked about what books I read from my college library, what
inspirations I took from "Wing of Fire - autobiography of A.P.J. Abdul Kalam" (I
had mentioned it in not-tech book names). I was asked about the problem solving
technique that I use in general life. I was asked about project life cycle. And then I have to wait outside for one more round.

HR Round: 
For, some people, there was HR round skipping MR. They informed me about only 2 questions: ‘Tell me about yourself’ and ‘Tell me your family background’.

I went to interview room. Askok Kolla was there. He started: "So, Sarang, Tell me about..." I just arranged the answer about myself and he said "Your College"!!! Oh! First time I was feeling on the spot that I would not aware anything about my college!!!
However, I managed. I was told to know my expertise why I should be hired in TCS. I mentioned my language independence like I know Java, Dotnet (and now SAP too). I told to be independent team member, who performs his task in time considering as his responsibility. Then, I was asked to weather I will go chennai for 2 years compulsorily if allocated, and then some policy questions. A complexity generated when I asked package. He told I
knew the package. So, he would not say, and he would not.

"Nice to meet you, Sarang. You will be informed later."
On 3rd of February, I came to know about selection confirmation in TCS. And my joining date is 14th March at Infocity, Gandhinagar, Gujarat (India), and a week past my birthday!