When I was an undergrad (Finished in 2007) it was different. You were definitely assigned to a program which had required courses with a 1-2 half courses a yearyou could use for other courses. They didn't generally limit what classes you could take and I filled out my schedule with computer science courses. This changed in my last year where they switched to a specialization / major / minor system where you could combine courses to more or less create your own degree. I ended up leaving with a specialization in biochemistry and microbiology and a major in computer science.