Michael Devore escribió:
Finally, I added two new options which don't follow Microsoft standard. Why the heck did I do that so close to FreeDOS 1.0 release?Well, I see no problems. In my opinion (and I think I've heard this before), compatibility requirement means that adding more options to a program is quite ok, provided that MS is a SUBSET of this....
The first option is X=TEST. This option tests all UMB blocks after X=<range> and I=<range> qualification by examining all bytes of the ROM block memory image. X=TEST will discard a block from being used as a UMB if it detects any byte value other than 0 or 0FFh, since those two values typically are found in unused upper memory.I don't know if I get this, so what is the use of X=TEST after X=<range>? If you have already explicitely forbidden that range...
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. Overwriting the ROM code obviously could cause serious problems and the standard EMM386 ROM-scanning method has no way to detect that code. X=TEST will detect the code and stop a UMB from being placed there. The paranoid may want to make it a default option.(maybe naive question) but why not simply adding this new second scanning algorythm to the existing one? (for the range specified with RAM= or for the default scanned range is no RAM present).
Aitor
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