Re: SPEEDOS and Func WZ

["Robert Holmgren" holmgren@xxxxxxxx]

** Reply to message from Patricia M Godfrey  on Mon, 17 Feb
2003 14:17:40 -0500


> on the whole, it looks as if XyW is using EMS, no matter how loaded

Yeah, it looks like you're right: the /E switch seems to serve to limit the
amount loaded, only. In fact, under WNT, if you specify the amount of EMS to
use (/e4000), it sets aside 4000Kb; if you don't specify anything, it sets
aside 4192Kb -- in other words, more than the supposed maximum amount; but if I
ask it to set aside 4192Kb using /e4192, that doesn't work! Obviously, it pays
to reverify assumptions -- I could swear I rechecked this a few months ago.
Hmmm. Let me try something -- OK, I know why I got different results. On my
present "travel" machine (a Thinkpad T23), the Universal Serial Bus BIOS
occupies memory region at DC000-DFFFF.  I have to stop the USB drivers to be
able to use EMS at all. If I then use the /E switch, EMS goes into that area;
if I don't, maybe the USB code still goes there?? But if I reboot the whole
machine and disable USB entirely at the BIOS level (instead of just unloading
the drivers), I get your results. Interesting. Therefore, it follows that
EMS, by default, must be located in that area (DC000-DFFFF). Gosh, I'm
terminally confused; I thought EMS was supposed to be mapped to E000. Maybe
modern memory managers just relocate it anywhere it finds a hole, I dunno. Or
maybe it's machine-dependent?

You're gonna need a larger tool bag to verify that the value of ZX really
doesn't matter. It's one thing to "set aside" a specified amount of EMS (which
happens at launch time), and another to actually use it. Obviously, when you
first launch, even though MEM /C shows that 4Mb are set aside, there's NO WAY
that more than a tiny portion of that could actually be in use. I can't think
offhand of a profound tool that would really nail that, by looking into EMS and
seeing what's there (there's probably something in the Resource Kit, but I'm
not very familiar with Windows tools). There used to be DOS tools like MEMWALK
that really looked into memory, but I tried using it several years ago under
Windows and it didn't work. Hmmm. DEBUG would show you that area -- if you
could find it (knew exactly where it was)! Sounds like a long quest, and
lsrgely of academic interest only ... I'd continue to use ZX=0 until we know
more (if ever). If the docs are right about "automatically" using EMS, they
may well be right about ZX.

-----------------------------
Robert Holmgren
holmgren@xxxxxxxx
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