Jordi Guillaumes i Pons Barcelona - Catalunya - Europa El 04/12/2012, a les 22:55, "Boyanich, Alastair" <Alastair.Boyanich at au.fujitsu.com> va escriure: I've not messed around with TOPS-10/20 and only VMS on simh, but there you need specify which O/S is running inside the VM and specify it with something like: set cpu idle=VMS Well, KLH10 os a different beast. You have to patch the guest OS to do a write to an " idler" device so the simulator knows the guest is not doing anything and it can enter a wait state until next timer tick or interrups happens. This patch is included in the Panda monitor and it works as expected... ... Unless you happen to be using a "high performance" host system (he, and the Pi seems to fit that class lol...). Then you have to build the simulator to use a synchronous implementation for the timers and device interrupts (see https://groups.google.com/forum/m/?fromgroups#!msg/alt.sys.pdp10/vHcQ49tjMa…) and the idler simply does not work at all. Unfortunately it seem there is no fix for this problem (see https://groups.google.com/forum/m/?hl=en&fromgroups#!msg/alt.sys.pdp10/…) so I will have to live with it. Not a big problem in the raspi anyway... (Apologies for the double post... The bus just caught a bump and my finger moved to the send button when I was completing the message :))