The only essential GCE A level for admission to Cambridge to read for the Computer Science Tripos is Mathematics. Also desirable are Further Mathematics and a physical science (Physics, Chemistry or Geology) at A level, or at AS level if not taken at A level. Candidates for admission may be encouraged to take the extension paper in Mathematics when it is available.
Those wishing to go on to Part IB Computer Science in their second year should take either the 50% option of Part IA of the Computer Science Tripos or the Computer Science option of Part IA of the Mathematical Tripos. The 25% option of Part IA of the Computer Science Tripos is principally intended for those who plan to continue with Natural Sciences in their Part IB year; it is not a suitable preparation for Part IB of the Computer Science Tripos.