>> A couple of corrections... more corrections ;) >> ...
>>> There is even an EMM286.EXE driver for machines with a 286 CPU floating >>> around >>> the Internet that basically does the same thing EMM386 from MS does >>> (including >>> providing virtualized EMS). >> >> Never seen that one. But the 286 memory managers I saw, such as >> BlueMax, used the _chipset_ to map RAM into UMBs, not the CPU. The 286 >> doesn't have a hardware MMU and can't do this. This meant that 286 >> memory managers were specific to the motherboard chipset. BlueMax >> worked on IBM 286 PS/2s and nothing else. There was also a Chips & >> Technologies one I read about. > I don't know exactly how EMM286 works -- it may be in fact be quite different > than EMM386. By it's description https://ibm-pc.org/drivers/memory/EMM286.ZIP it's essentially the same as the starter of this thread https://www.emsmagic.com/. «EMS Magic is an expanded memory (EMS) emulator for DOS programs. simulated EMS, but no UMB. > I do know that it provides essentially the same functionality as EMM386. > Also, if you use the EMS provided by EMM286, it seems to reboot the CPU to > exit the Page Frame (i.e., it is VERY slow and isn't as useful as it is with > EMM386). AFAIR rebooting a 80286 required some order of millisecond(s). While far slower then a 80386 (didn't require this reboot), but but much faster then a disk access which is was often used to access data > 640KB. So it's usefullness depended on the way the program would use EMS. >> x86-64 removes support for V86 mode, and I believe, for 286 protect mode too. Nope. a current X64 still has real mode and V86 mode. However both are not available with a 64Bit host OS. AFAIK 286 protect mode too is available from x86-64, too. However there are so few 286 protected mode programs in the wild, that they are rather irrelevant. They all died with OS/2. Insofar 8088 mode programs (Lotus 1-2-3 r2, Wordperfect, SuperCalc, As Easy As, Quattro Pro) are probably much more relevant. And that's where the thread started;) Tom _______________________________________________ Freedos-devel mailing list Freedos-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-devel
