Hi Uli and Abe, indeed it seems like it is not trivial to find the right excluded areas for UMB to have stability. Having no page frame is okay - EMS 4 aware software can still use EMS, only EMS 3 software will miss a frame.
Normally it is enough to have 550k conventional free. To explain the different memory types: low DOS memory - the usual 640 kB that you always use, where you want to have at least 500 something free. HMA - provided by HIMEM - lets mainly DOS kernel load high XMS - provided by HIMEM - lets various DOS programs enjoy extra megabytes (ramdisk, dos extenders, caches etc.) UMB - provided by EMM386 - lets you load various drivers high, can also be provided by UMBPCI or other hardware drivers, can cause stability issues in conflict cases EMS - provided by EMM386 or old special hardware - lets old DOS programs enjoy some extra memory for page swap and extra data storage, not often needed by modern apps VCPI - provided by EMM386 - lets DOS extenders share the protected mode with EMM386, so if you do not load EMM386 in the first place, you will not need VCPI either. The special GEMMIS feature is similar, but for Windows 3. DPMI - provided by Windows and some DOS extenders - lets programs which use DOS extenders share protected mode, popular for modern games. Often, games come with their own DPMI driver to be able to run outside of Windows, using XMS or raw memory in that case. Raw memory - if you use protected mode "by hand", you can of course use all those megabytes outside the first DOS megabyte-and-a-bit, too. But using XMS or DPMI often is more convenient. What does this tell you for normal users? You should load HIMEM for HMA and XMS. If you need space to load drivers high, you should also use EMM386. The rest will be magic DOS extender use of whatever suitable memory you have and only in rare cases you would actually need EMS :-) Note that HIMEMX and XMGR are like HIMEM and JEMM386 is like EMM386, while JEMMEX is like both HIMEM and EMM386 combined into a single driver, with some pros and cons. Regards, Eric ------------------------------------------------------------------------------ Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San Francisco, CA to explore cutting-edge tech and listen to tech luminaries present their vision of the future. This family event has something for everyone, including kids. Get more information and register today. http://sdm.link/attshape _______________________________________________ Freedos-user mailing list Freedos-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-user
