This is just to let you know that there is a "show stopper" bug in Nachos version 3.1. (The bug does not exist in 3.0, for those of you using that version.) The bug exhibits itself as seg faults for some programs that use multiple threads. I have fixed this bug, and the fix is available as Nachos, version 3.2, available from ftp.cs.berkeley.edu. Anyone currently using 3.1 should immediately grab the new version. Those using 3.0 can grab the new version at your leisure; the two advantages to 3.2 over 3.0 are: (i) works on SPARCS and (ii) unmapped pages bounding each thread execution stack, to automatically check for stack overflow/underflow. It was this second feature that caused the bug requiring this new release.