hi "Speculative Execution" is a feature of the R10000 Processor. I read that is problematic on machines that are Non-Cache Coherent, such as the IP28 Indigo2 and on R10000/R12000-based IP32 O2 systems. The first thing I don't understand is what does it mean that they are "Non-Cache Coherent" systems. I mean, I know what coherence of the cache means in a multiprocessor environment, but I'm a bit confused by what I read for these mono processor systems. A few more details on the nature of Speculative Execution, and the issues it poses to the Indigo2 can be found at the following URLs: 1) MIPS R10000 Microprocessor User's Manual (pages 51-55 ) https://web.archive.org/web/20051028113506/http://techpubs.sgi.com/library/manuals/2000/007-2490-001/pdf/007-2490-001.pdf 2) Post to NetBSD sgimips Mailing List on 29 Jun 2000 http://mail-index.netbsd.org/port-sgimips/2000/06/29/0006.html however there are no examples. Can someone explain this matter to me? Thanks