Hi Ray SHMEM_BASE_ADDRESS is used as a "key" for shared memory in rtlinux systems that do not use mbuff or rtai_shm. This usually points to the start of a reserved block of upper memory as specified in lilo's "mem=xxMb". Regards, Paul. On Monday 09 Sep 2002 2:35 pm, Ray Henry wrote: > What is the current function of this ini variable? > > Ray