There is no specific rule barring the use of slide rules during an AP exam. However, it could be argued that slide rules work similarly to a calculator, so it is tricky to bring slide rules into the exam room for AP exams that prohibit calculator use. As such, various test centers might have differing rules for taking slide rules into your exam room. If you’re interested in using a slide rule during your exam, reach out to your AP coordinator beforehand to avoid any misunderstanding.