(The math department recommends TI-83/84 regular, plus, or silver.)
Precalculus: A graphing calculator is recommended and will be used at the teacher's discretion. If you do not have a graphing calculator, one will be provided in class, but you must have at least a scientific calculator to use for homework.
Calculus: A graphing calculator is required for calculus and may be used at all times. If you have a calculator with symbolic algebra (like TI-89), understand that written work will be required wherever appropriate.
(link to TI information site)