I have a virtual disk image file os9000-xibase.img and Windows can't read it nor mount it.

With ImDisk Virtual Disk, I'm able to mount it, but not read it, because it is a Random Block File System disk image of 'Microware os-9 (which is now maintained by Radisys)'. Edit: Qemu image

I was wondering if there was any tool available to make RBF discs/diskettes readable in a file-manager like windows explorer.

I found 2 tools: OS9Max, but that is through a terminal and costs money.

The other tool I found was for Linux 2.6, but I couldn't get it to compile, can somebody else get it to work?

Does anyone know an Explorer-like tool, to help me view the contents of this RBF Image? Edit: Qemu image

I reposted this on SuperUser , on Software Recommendations and on AskUbuntu.

Edit: The link I got it from was: http://lsw.ee.hm.edu/~tasin/qemu-and-os9000/OS9000-4.9_on_QEmu-with-XiBase9_en.zip

It turns out it was very easy to run, once entered xb , it looks exactly like windows XP, It was a Qemu image, thus a virtual harddrive, not an installer.

  • 1
    I found this RBF fileformat description in case someone want to code it ... However it looks like the img file does not match (size of sector, cluster and number of sectors is wrong) or the img is encoded differently
    – Spektre
    Commented Aug 27, 2019 at 9:33
  • 1
    This isn't really retro, as it will run on modern hardware.
    – scruss
    Commented Aug 28, 2019 at 13:57
  • Where do they else talk about os-9
    – Ciel Ruby
    Commented Aug 28, 2019 at 23:55
  • 1
    @KevinCrans - Tandy CoCo users, NitrOS9 users: that's where. The image you posted was x86 OS-9000 for a relatively recent PC: almost unrecognizable from what little I'd remember from OS-9 on 6809
    – scruss
    Commented Aug 29, 2019 at 21:52
  • Sorry, but I didn't know until this issue was solved that it was modern. Thank you for pointing me to those sources. I'm planning to work with os-9 2.4 though.
    – Ciel Ruby
    Commented Aug 30, 2019 at 11:04

1 Answer 1


ToolShed seems to be the current maintained OS9/descendants disk manager tool. It's not a file browser but works on the command line.

Are you sure your disk image is a valid RBF image, though? Toolshed refuses to read it:

$ os9 dir os9000-xibase.img
dir: error 216 opening 'os9000-xibase.img,'
dir: error 216 opening 'os9000-xibase.img'

Similarly, checking the image gives this:

$ os9 dcheck os9000-xibase.img
Volume - '3' in file: os9000-xibase.img
$D0BC bytes in allocation map
124 sectors per cluster
$FA33C0 total sectors on media
Sector $8BF450 is start of root directory file descriptor
Building secondary allocation map...
Sector wrong size, terminating (001).
LSN: 9172048

Update: the image is a PC hard disk image for Virtualbox/QEMU, and it contains a demo of OS/9000 for x86.

  • 3
    Maybe some ill endianess problem?
    – Janka
    Commented Aug 26, 2019 at 20:50
  • 5
    I looked at a hex dump of the file and found what appears to be a directory, except that each directory entry is 64 bytes. The only OS9 RBF documentation I found in a quick search claimed that directory entries should be 32 bytes long. So I'm thinking this isn't really an RBF image. It looks like the first sector has an MBR partition table in it (including the 55 AA signature bytes), so this may be a PC hard disk image.
    – Ken Gober
    Commented Aug 27, 2019 at 2:07
  • Thank you very much for your comment. For information, the Disk came with Qemu. If it's not RBF, what could it then possibly be?
    – Ciel Ruby
    Commented Aug 27, 2019 at 14:32
  • 1
    It's an Qemu Image. I usually use Virtualbox or VMWare.
    – Ciel Ruby
    Commented Aug 27, 2019 at 15:32
  • 1
    Yes, it's a PC hard disk image, not RBF. Loads up fine in Virtualbox
    – scruss
    Commented Aug 28, 2019 at 1:47

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .