Hello

To get admission in Diploma in Computer science you don't need to have class 12th marksheet. To be eligible for this course you need only class 10th marksheet. The admission is merit based. There is no entrance examination for this course. You have to send the application to the college. Then the college announces the cut off. If you clear the cutoff then you can take admission in that college.

To know more refer this

https://www.careers360.com/courses/diploma-in-computer-science

Good wishes !