You do not have to worry about this anymore. That used to be a function for way back in 10/11... In the early days of AutoCAD, it had to page dwg info out of memory to the disk when needing more memory! The H'disk was being used as virtual memory, but the paging was very slow on DOS. There used to be a ceiling of 45K that was allocated to 640K DOS, bigger programs than that had to use vmon to do paging which unfortunately worked only on user-defined functions but not on variables or strings. Typically programmers where using a CLEAN routine manipulating the ATOMLIST. Maybe that is what you were looking for on a different thread!