COSC101 currently runs in both first and second semesters with 12 Lecture groups and 40 Lab groups. If you cannot register for the course in the first semester, note that it is because the lectures and lab groups are filled up to the required capacity. In such situation you should register for the course as COSC101 in the second semester not COSC102.
Download all lecture materials for the course
Check the lecture and the lab time table here. View the course syllabus here