At 04:03 PM 4/26/2004 -0400, Patrick J. LoPresti wrote: >Michael Devore <[EMAIL PROTECTED]> writes: > >> Is X=TEST really necessary? Unfortunately yes, at least for some >> machines. There exist PC's which place ROM code in the upper memory >> area, but without the standard ROM signature of 55h AAh. These >> aren't old moldy machines either. In a small test pool, at least >> two Pentium 4 class machines placed disk driver code in upper memory >> areas without using ROM signatures. > >Do you know whether/how Microsoft's EMM386 deals with this? > >Just curious.
I don't know. Two conjectures, though. Conjecture the First: they implement the same memory compare we do in X=TEST automatically. Doubt it, frankly. Conjecture the Second: they use a means I don't know of such as a BIOS memory map call, or a chipset-lookup ID-specific support function, or card communication magic to figure it out. No clue as to how likely this would be. UMBPCI does do chipset-specific things, but I can't figure the German comments in the source well enough to know whether it's related . Bonus Conjecture the Third: they put the burden on the vendors and users to eXclude the problematic areas from UMB use. Sounds like what the evil side of Microsoft would do, but they actually work pretty hard on compatibility, so I'm thinking this isn't it, either. ------------------------------------------------------- This SF.net email is sponsored by: The Robotic Monkeys at ThinkGeek For a limited time only, get FREE Ground shipping on all orders of $35 or more. Hurry up and shop folks, this offer expires April 30th! http://www.thinkgeek.com/freeshipping/?cpg=12297 _______________________________________________ Freedos-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/freedos-devel
