Hi Francisco,

> When I attempt to start the FreeDOS using VirtualBox, I get the following DOS 
> screen:
> It says:

> JemmEx v5.75 [05/21/11]
> System memory found at c900-dfff, region might be in use

This may mean that JEMMEX has doubts about whether that area
is suitable for use as UMB area. You could exclude the area,
to be on the safe side. Or even skip loading JEMMEX completely
and load only some XMS and HMA driver instead, such as HIMEM.

You can also load neither HIMEM nor JEMMEX, but then you will
not be able to use XMS or HMA. Less DOS memory will be free.

If you only skip JEMMEX but load HIMEM, you will not have EMS
or UMB memory. Most software for DOS is happy with XMS, so it
does not need EMS, but without UMB, you can not load drivers
and other resident software outside the first 640 kB of memory
so you will have a bit less DOS memory free.

> JemmEx loaded
> Kernel: allocated 46 Diskbuffers = 24472 Bytes in HMA

At this moment, HMA becomes available and the FreeDOS kernel
starts to use it. You probably mention the message because
that is exactly the moment when DOS hangs in your VirtualBox?

It is possible that trying to use HMA, XMS or UMB, some driver
or the kernel accidentally got in conflict with memory used by
your VirtualBox BIOS or virtual hardware for something else,
causing a crash. Your JemmEx message warns about such a risk.

It also is possible that "A20 switching" of your JEMMEX caused
problems by either crashing or having no effect, but as it has
various A20 styles available, you could try non-default styles.

Please read the documentation of JEMMEX and edit your config
sys (or fdconfig sys) file to use more "cautious" options for
JEMMEX. Alternatively, simply skip loading JEMMEX completely,
for example using the usual F5 or F8 hotkeys or, if you have
a menu defined in your (fd)config sys file, by selecting one
of the boot configs which use other drivers than JEMMEX :-)

> Any help would be appreciated.Thanks

It is possible that changing the type of virtual harddisk, USB
or network controller or virtual A20 hardware can help, too! :-)

Regards, Eric

PS: You have not specified where the "FreeDOS 1.1 VDI" VM image
came from and which versions of what and which configs it uses.

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