On Mon, Tue, 16 Mar 2004 07:22:32 +0200, Luchezar Georgiev wrote: > In no case the space F0000-F6FFF is "all ones" (FFs),
If I just looked for "all ones", I would find close to nothing ;-) > but the BIOS just > "forgets" to set it so after its initialisation, since it's officially > reserved for it. But in fact it doesn't really use that space, so you can > force EMM386 to use it by /I=F000-F6FF and it will work! :-) The upper > limit varies (is not necessarily F6FFF) and can be determined by (1) > trial-and-error, I always try to find good candidates for reusing as UMBs by looking for the strings displayed in BIOS Setup and during POST, then round them to the nearest 4K boundary and try whether the system hangs (it not necessarily happens immediately after loading EMM386 and all drivers/TSRs, sometimes you need to run several applications to experience a crash). Then I try to enlarge this area (or narrow it, if it does not work). In all cases I had to leave at least one 4K block at F0000 for ROM BIOS to avoid crashes. This method does not necessarily work on systems where you can enter Setup at any time (and even leave it without rebooting, if hardware configuration is unchanged). > and (2) looking at the interrupt vector table to see > where is the lowest interrupt handler addres. Life isn't as simple, unfortunately. Sometimes interrupt handlers jump around the whole BIOS area, and sometimes they call subroutines at distant addresses. I do not remember it clearly now, but in one case I even managed to locate the subroutine which was the culprit; anyway, I do not have this mainboard any longer (I do not even remember its brand). >> This is very vendor/model-specific. > Of course, and is valid for Award BIOS only. Not for all sub-models, I am afraid. (I don't think that the brand of EMM386 matters here, but in most cases I tried DR-DOS EMM386 only.) But I have also heard quite long time ago that on many machines you can reuse whole 32K at F0000-F7FFF. I believe. I just never succeeded. Michal ------------------------------------------------------- This SF.Net email is sponsored by: IBM Linux Tutorials Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click _______________________________________________ Freedos-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/freedos-devel
