a change marked XXX, where gcc -Wall pointed out a bit of the original
code that looked wrong. The jury's still out on whether or not it was
really wrong, but it looked _very_ suspicious.)
Reference Design NetBSD source code, obtained from the pages under
http://www.research.digital.com/SRC/iag . Some of this code (badly)
needs to be cleaned up, and as-is it doesn't compile. However, getting
it in the tree is a start.
