Is computer science available at IISER Pune or other IISERs?

No, you can’t choose Computer Science as a major at IISER Pune or any other IISER. But you can definitely learn basic Computer Programming and techniques. You will have the opportunity to learn various languages and there are also different labs where you can do theoretical and computational work. Course work of many departments depends heavily on computational work at IISERs. But there is no option to take Computer Science as a subject.