Ticket #11172 (new enhancement)

Opened 3 years ago

Last modified 3 years ago

5.25 inch floppy image wont work/mount correctly in Virtual Box

Reported by: DrSvenne Owned by:
Priority: minor Component: virtual disk
Version: VirtualBox 4.2.4 Keywords:
Cc: Guest type: other
Host type: Windows


I discovered some old 5.25 inch (360 KB and 1.2 MB) Floppy Disks which I scanned with WinImage to generate *.IMA-files, they mounts correctly in Virtual Box and I can run DOS 5.0 and 6.22 as VMs. However when trying to format the floppy images from within the VMs, VirtualBox seems to assume that all floppy images is of 1.44 MB size and thereby crashes and corrupts the *.IMA files.

Also the same problem seems to occur when using 720 KB floppy images.

I know that this might be an obsolete feature, but the fact was that I had very old backups on these floppys, which I thought I had lost, and it was fun to rediscover them. However I needed to creat a DOS 5.0 and 6.22 VM in order to unpack and use the backups.

(With todays PC hardware its not possible to install an old DOS 5.x or 6.x system, therefore using VMs instead)

Besides that VirtualBox seems not to be able to mount *.IMZ files created by WinImage (= compressed IMA-files)

There is another strange behaviour of VirtualBox when running DOS 5.x and 6.x as VMs and its that the VMs tends to almost lock the CPU at 50-100 % load all the time.

Also character mode DOS apps, like Borland TurboPascal and EDIT.EXE cannot be correctly resized when run in DOS as VM, the window remains small.

Change History

comment:1 Changed 3 years ago by Echoes

I can agree on the floppy problem (it seems to me you cannot force anymore the drive type like in "", not even by modifying the VM configuration file). We need either better support either by specifying it in the drive properties or by setting the BIOS drive type value (like in VMWare and VirtualPC where you can access the BIOS screen).

IMZ files are used only by WinImage and no other VM software can actually used them. Considering that the biggest floppy image you'll probably need to store is about 1.72/2.88 mb it's not a big deal.

The CPU load is a problem of DOS and not a VirtualBox behaviour. See and for a description of the problem and a solution for DOS (in the comments on virtuallyfun) and Win 3.x.

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