[comp.os.msdos.programmer] HIMEM.SYS problem on 486 machine.

slahiri@magnus.acs.ohio-state.edu (Santanu Lahiri) (06/28/91)

Hi Folks,

I ran into a weird problem installing DOS 5.0, and I'd like to know
if anyone else has experienced this.

I installed 5.0 on a 386 machine, and it worked fine.  Well, that means
DOS loaded into High Memory, although, for the life of me, I could not
get more than 529K free (I am running SmartDrive, RamDrive, SetVer, 
NEC's CD-ROM driver, Mouse Driver, DecNet drivers, MSCDEX and CED, so 
perhaps that's understandable).

Next, heady with the success of an easy (well, relatively) installation,
I offered to help a friend install his 5.0 on his 486 machine.  This monster
sported a 220M drive, and 8M memory, so I figured "No Problem."

Wrong.  The Setup Program ran without a hitch.  However, on rebooting,
the first message I get is

       HIMEM.SYS Extended Memory Manager  (or some signature)
       Cannot control A20 address line, aborting

After that, everything loads low.  I tried setting the A20CONTROL:ON option
that produced the message "A20 Address line already turned on" but no other
effect.  A20CONTROL:Off succeeded in locking up the machine big time.

Disgusted, I tried substituting QEMM386.SYS in place of HIMEM.SYS, and 
voila!  Everything works like a champ,  DOS loads high, Resident programs
load high (including smartdrive, ramdrive, CD-ROM driver, MSCDEX), and I
still have 619K available (after a little tinkering with Optimize).  Even
Windows runs without a hitch.

So what is wrong with HIMEM.SYS?

Does anyone know?
-- 
Santanu
-------------------------------------------------------------------------------
:: cat flames > /nev/dull                     slahiri@magnus.acs.ohio-state.edu

jcmorris@mwunix.mitre.org (Joe Morris) (06/28/91)

slahiri@magnus.acs.ohio-state.edu (Santanu Lahiri) writes:

>Hi Folks,

>Next, heady with the success of an easy (well, relatively) installation,
>I offered to help a friend install his 5.0 on his 486 machine.  This monster
>sported a 220M drive, and 8M memory, so I figured "No Problem."

>Wrong.  The Setup Program ran without a hitch.  However, on rebooting,
>the first message I get is

>       HIMEM.SYS Extended Memory Manager  (or some signature)
>       Cannot control A20 address line, aborting

What type of system is this '486 with the problems?  Some configurations
can't be reliably detected by HIMEM's code and you have to tell it which
platform it's running on.

Section 2.15 of README.TXT describes this procedure.

You may have a machine which isn't listed there but still requires some TLC.
Try calling Microsoft; they may know a special switch required by your system.
(Or if you post it to the net maybe someone else will know the magic 
incantation.)

Joe

schuster@panix.uucp (Michael Schuster) (06/28/91)

In article <1991Jun27.202435.16001@magnus.acs.ohio-state.edu> slahiri@magnus.acs.ohio-state.edu (Santanu Lahiri) writes:
>
>Wrong.  The Setup Program ran without a hitch.  However, on rebooting,
>the first message I get is
>
>       HIMEM.SYS Extended Memory Manager  (or some signature)
>       Cannot control A20 address line, aborting
>

HIMEM.SYS has got to be the most finicky device driver I've ever seen.
It uses a different strategy to control the A20 line on many different
types of machines, and "guesses" incorrectly on a lot of clones.
How QEMM386 and 386^MAX do it so transparently is beyond me.
Try playing with the /MACHINE:n (n ranges from 1-17 or so) command
line switch (it's documented in the README file) until you find
the right one.


-- 
                Mike Schuster                      |   -CIS: 70346,1745
-NY Public Access UNIX:  schuster@panix.com        |   -MCI Mail, GENIE:
-The Portal (R) System:  schuster@cup.portal.com   |           MSCHUSTER