Hi Paul, *On Friday 01 December 2006 15:56, Craig Gadd wrote: *> Package rtai-headers is a virtual package provided by: *> rtai-dev-2.6.16.18-rtai 3.3-4+2 *> rtai-dev-2.6.16.20-rtai 3.3-5+1 *> rtai-dev-2.6.16-rtai 1 *> rtai-dev-2.6.12.6-rtai 2 *> You should explicitly select one to install. *> *> I know I need to include some additional information in get-build *command, *> but am not sure how to include it, can you help me out? * *You need to install the rtai-dev package that corresponds to the kernel *running on your machine - `uname -r` will provide the necessary version *number, or you can use: * * apt-get install rtai-dev-`uname -r` * *This will also pull in the correct kernel-headers and compiler versions for *you.. * To recap, I managed to install the development tools, download the source code and add a -DSIMULATED_MOTORS to the RTFLAGS line in src/Makefile.inc. So last night, I did the following from /src as root: ./configure Make Sudo make modules_install (hopefully this is what you meant when you said to run make modules_install)! Everything recompiled at this point and it appeared to complete successfully. When I launched generic.run however, I still had the same problem with the x-axis display freezing when I manually spun the motor shaft. So as an experiment, I increased the max acceleration and velocity values in the generic.ini file to 100000 and that seems to have solved the problem. I felt like an idiot for not trying that before recompiling everything but at least I now know how. Thanks again for the help Paul. Craig