Normally, yes, that's what you'd do. But it is possible to use more than 256 K without the KT24 memory map/bootstrap module, assuming your OS never tries to do I/O to memory past 256 K. For example, RT-11 SJ, where the extra memory is used as a virtual (VM:) disk drive. -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology WWW: http://www.trailing-edge.com/ 7328 Bradley Blvd Voice: 301-767-5917 Bethesda, MD, USA 20817 Fax: 301-767-5927