Computer Science 237
Computer Organization

Lecture 33: Traps/Exceptions/Interrupts
Date: December 2, 2005

Last CS Colloquium of the semester, this afternoon, 2:30 PM, TCL 206. Jamieson Cobleigh from UMass.
Mary wants the tables back in the digital logic lab - please tear down your memory circuits.
Phase 2 due today. I hope this is not a surprise.

Microcode questions/answers
- New test: jing.s
- I/O clarification: input in tinput, output in toutput by default.
Traps, Exceptions, and Interrupts
- A trap is a subroutine-like call that occurs automatically to handle some condition. The condition is usually resolved quietly and life continues on.
- An exception is a more serious trap that might not involve recovery from the instruction.
- An interrupt is a (usually asynchronous) external request for the CPU's attention.
- Supervisor mode vs. user mode
- Interrupt vectors