If you are in your 12th or you have completed your 12th in any stream, you are eligible for studying CS Foundation. You need to provisionally register for CS at their official website. And your CS Foundation registration holds good for 3 years. Now there is no entrance examination. Once you register, you will have to complete the study period with the study material given and then appear for the Foundation exams. For more information, please visit the official website : https://www.icsi.edu/media/webmodules/student/GUIDETOCSFOUNDATIONCOURSE.pdf