First of all, if you are good at technical skills, this company is one of the best company for you.
The selection process comprises of 5 stages:
1) Technical objective paper
2) Technical subjective paper
3) Technical interview 1
4) Technical interview 2
5) HR interview
The technical paper will not be tough if you have taken your subjects in engineering seriously or if you have prepared for GATE previously, its an advantage for you.
Main subjects of concern were:
* Data Structure
* Software engineering
* Concepts of C
This is the order of priority too.
First written paper comprises of 60 questions to be attempted in 60 mins
5 from Data structures 5 from C
5 from S/W engineering 5 from dbms 5 from OS and Computer system architecture and 5 from general aptitude
Your basics must be clear in all these subjects.
Next, the second written test is taken consecutively so be prepared. It has two questions, one from English prose writting and another from C question from English will be based on some very general topic on which every one can write atleast 2 pages (but dont write so much), the next question is to write a C program based on some nice logical problem. We were asked to write a program to read all sentences from one file, remove extra spaces(more than one consecutive spaces) between two words from each sentece, and write the modified sentences to another file.
If you have survived till now, here starts your main race. Both the technical interviews will require you to prepare all the above mentioned subjects in great depth. Prepare your project too.
You would be asked to write programs, write algorithms, solve puzzle type questions, about the toughest part in implementing your project, etc
If you have still survived, you will get through because they don't filter much in HR round. My HR round was a cake walk. Although my technical interviews lasted for 1:30 hours and 45 mins respectively.
HR interview was hardly 20 mins.
Best of luck see you in Persistent!