Message-Id: <s492a018.006@calderauk.com>
Date: Sat, 13 Dec 1997 14:47:20 +0000
From: Matthias Paul <MPaul AT calderauk DOT com>
To: opendos AT delorie DOT com
Subject: Re: memmax question
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Hi Dinko, hi all

>When I run mem ith shows 615KB for largest executable program size and
>about 714KB total free dos memory, but when I run memmax it maps the
>video memory space but the largest exec siye stays at 615 KB and to
>total DOS memory is reset to 615 KB (which is of no use for me).
As far as I understand your problem, you are trying to switch MEMMAX +V
and -V back and forth, which leaves the largest program size at 615KB 
(though you were expecting it to blow up to 714KB with +V), and also 
reduces the formerly reported value of 714KB free DOS memory downto
615KB after playing with the +/-V option. Is this correct?
Though it is not usual, that the values change after toggling, as far as 
know, it can happen as MEMMAX has to apply changes to the MCB chain.
I encountered similar changes in the reported values, when toggling
+/-V while switching between the two monitors of a SVGA+Hercules 
system. However, this only changed the size of the video memory area,
so that I sometimes was loosing 32KB of video memory address space.
This problem can be worked around easily by changing the sequence of
switching the video systems and the +/-v option, whereas this is not possible
for your problem.

I can see only one of the following reasons: 

- An eXtended BIOS Data Area at the end of the 640KB area, which is not
  automatically moved by HIMEM/EMM386 (usually it will be moved if
  /VIDEO is enabled and you are not giving the /XBDA option). Some
  ATs (especially AMI) provide a Scratch Pad option in the CMOS setup,
  some newer machines have a CMOS option where to store the XBDA
  area. Changing this setting may help.
- The following is not applying to your computer:
  Machines with less than 640KB conventional memory or (without EMM386
  loaded) with non-standard video hardware (continous (video) RAM at A000+
  is necessary for HIMEM /VIDEO, whereas EMM386 /VIDEO just maps in 
  virtual RAM at these locations). BTW, with /USE the new EMM386 is also
  able to backfill memory into the video memory area, when been used as
  permanent UMBs (nice option get more UMBs for those, who don t do
  graphics).
- In a few cases, there might also be another driver loaded at the upper end 
  of conventional memory (some disk/security drivers do, some resident 
  anti-virus software does, few viruses do too).

A MEM /A output, the CONFIG.SYS calling parameters of HIMEM/EMM386,
and any programs calling parameters which MEM reports as being loaded
at ca. 9000-C800 might help to better locate the problem.

>the only other nonstandard thing that happens while booting is that EMM
>reports that A20 line is in use. I tried to use the /GATEA20 switch but to no
>avail.
Hm, I see no connection, but anyway try to solve the problem by changing
CMOS setup options, or try all /GATEA20= values: AT, HP, MCA, PS2, XMS.

Matthias


------------------------------------------------------------
Matthias Paul
eMail: <Matthias DOT Paul AT post DOT rwth-aachen DOT de>
Web: http://www.rhrz.uni-bonn.de/~uzs180/mpdokeng.html