Upper memory not fully available under VirtualBox

[t6ti00]

I've been running MS-DOS/Win 3.11 virtual machine successfully for years on Microsoft Virtual PC and had 80 624 K of upper memory available. I have set up AUTOECE.BAT and CONFIG.SYS successfully to load some files into upper memory.

Today I started testing with newest version of VirtualBox and used existing *.VHD-disk image, so AUTOEXEC.BAT and CONFIG.SYS are unmodified. I get only 4 080 K of upper memory.

I have read viewtopic.php?t=7566 and used search-button as well looking for solution. I have tested tweaking memory options and other things as well, but there are still 4 080 K of upper memory available.

Is it true that FreeDOS is only solution to be used with VirtualBox, or are there other ways around?

Thanks.

[michaln]

I don't know what you call "upper memory" but it's not what you think. It's the region between 640K and 1MB which can be backfilled with RAM and there's never more than ~150KB available. But you're talking about 4 to 80MB... so what are you talking about?

[Perryg]

I'm slightly confused as well. I have everything LoadHigh and here is what mem reports for me.

DOS-U-mem.png (23.11 KiB) Viewed 8329 times

DOS-mem-u2.png (26.01 KiB) Viewed 8329 times

[michaln]

Might as well upload the MEM results from one of my DOS VMs... note that I'm using the I= parameter of EMM386 to get more UMBs and EMM emulation is disabled.

[t6ti00]

I don't know what you call "upper memory" but it's not what you think. It's the region between 640K and 1MB which can be backfilled with RAM and there's never more than ~150KB available. But you're talking about 4 to 80MB... so what are you talking about?

Oh yes... commas are missing here!

Here are what I got:

VirtualBox 4.1.6 (above) & Microsoft Virtual PC 2007 (below)

[vbox4me2]

Show us contents of config.sys and autoexec.bat + screenshot of only the mem command.

[t6ti00]

Here are the contents:

AUTOEXEC.BAT

@ECHO OFF
PROMPT $p$g
PATH C:\WINDOWS;C:\DOS;C:\MOUSE
SET TEMP=C:\WINDOWS\TEMP
LOADHIGH KEYB SU,,C:\DOS\KEYBOARD.SYS
LOADHIGH C:\DOS\MSCDEX.EXE /D:MSCD001 /L:E
LOADHIGH DOSKEY
SHARE

CONFIG.SYS

DEVICE=C:\WINDOWS\SMARTDRV.EXE /DOUBLE_BUFFER ¦
DEVICE=C:\DOS\HIMEM.SYS
DEVICE=C:\WINDOWS\EMM386.EXE NOEMS
DOS=HIGH, UMB
BUFFERS=20
FILES=40
LASTDRIVE=H
STACKS=0,0
COUNTRY=358,,C:\DOS\COUNTRY.SYS
DEVICE=C:\MOUSE\MOUSE.SYS
DEVICEHIGH=C:\DOS\CDROM.SYS /D:MSCD001

...and screenshots:

VirtualBox 4.1.6 (above) & Microsoft Virtual PC 2007 (below)

[stefan.becker]

Its easy to solve, install XP as guest

What do yo want with such amount of himem? If you dont use 4 MB or 80 MB?

[vbox4me2]

Try: DEVICE=C:\WINDOWS\EMM386.EXE RAM ON NOEMS FRAME=NONE I=E000-EFFF I=B000-B7FF
It gives more ram but you will need to tweak more to get more.

[michaln]

t6ti00: No, commas weren't the problem, you just don't appear to understand the difference between a byte and a kilobyte... You said you had 80 624 K upper memory in VPC, but you apparently meant 80,624 bytes. That was very confusing because such amounts of upper memory are impossible.

Anyway, the EMM386 I=xxxx-yyyy arguments should fix it. Including the B000-B7FF region is safe, so is the CC00-DFFF region and in 99.9% cases, also the E000-EFFF region.

If enough users complain that EMM386 does not automatically detect the available UMB regions, it might even get fixed. Feel free to open a ticket about this and mention that it works in VPC (and/or whichever other virtualizer it works in).

[t6ti00]

Its easy to solve, install XP as guest

What do yo want with such amount of himem? If you dont use 4 MB or 80 MB?

Actually I have XP as host. I am just one of those people who still enjoy working with real MS-DOS now and then. I'm sure you know already that some programs needed a lot of free conventional memory back in time.

Try: DEVICE=C:\WINDOWS\EMM386.EXE RAM ON NOEMS FRAME=NONE I=E000-EFFF I=B000-B7FF
It gives more ram but you will need to tweak more to get more.

Thanks, it worked!

t6ti00: No, commas weren't the problem, you just don't appear to understand the difference between a byte and a kilobyte... You said you had 80 624 K upper memory in VPC, but you apparently meant 80,624 bytes. That was very confusing because such amounts of upper memory are impossible.

Anyway, the EMM386 I=xxxx-yyyy arguments should fix it. Including the B000-B7FF region is safe, so is the CC00-DFFF region and in 99.9% cases, also the E000-EFFF region.

If enough users complain that EMM386 does not automatically detect the available UMB regions, it might even get fixed. Feel free to open a ticket about this and mention that it works in VPC (and/or whichever other virtualizer it works in).

I have to admit that I mix bytes and kilobytes now and then. Thanks to you, too.

It's now solved here. I opened a ticked about the issue.