On Mon, 07 Jun 2010 09:55:36 +0200, you wrote: 3. Oh well, it would be nice to learn where is the culprit and how to rebuild a TOPS-10 monitor from scratch! :-) Now I've posted a request to alt.sys.pdp10. Let's see if someone will explain me what to do. Hello again! As I wrote, I posted a plea for help in alt.sys.pdp10 and obtained some very useful answers. They explained me how to patch the monitor binary file and now the CPU hosting the KLH10 emulator is only 0.5% busy when TOPS-10 idles. It's a very easy task and takes less than a minute to complete. If someone is interested I can describe it here, or can go read the thread on the NG. Back in topic, now I'll head on to a complete DECnet-10 setup (in my scarce spare time). :-) Do there is someone here that has suggestions on this? Bye, G.