Floppy disk image formats supported by Virtual PC and Virtual Server

Virtual PC and Virtual Server allow you to create and use 1.44MB (high density 3.5" media) and 720KB (double density 3.5" media) floppy disk images.  However they also support a number of other formats.  The supported formats are as follows:

Size: 360KB
Format: Single-density
Media type: 3.5"
Information: You probably are unfamiliar with this format.  The only place that I've ever seen this used is on the old Apple Macintosh installation media.

Size: 720KB
Format: Double-density
Media type: 3.5"
Information: This is the standard "old" 3.5" floppy disk format.

Size: 1.2MB
Format: High-density
Media type: 5.25"
Information: This is the largest standard format that was supported on the old, flexible, 5.25" floppy disks.

Size: 1.44MB
Format: High-density
Media type: 3.5"
Information: For people who are still using floppy disks, this is probably what they're using.

Size: 1.68MB
Format: High-density - DMF
Media type: 3.5"
Information: DMF, or Distribution Media Format, was a format used by Microsoft to allow them to cram more data on to a standard floppy disk.  It was used for the installation media for things like DOS, Windows 3.11 and Office 4.2.

Size: 1.72MB
Format: High-density - XDF
Media type: 3.5"
Information: XDF, or eXtended Density Format, was IBM's equivalent to DMF.  It was used for OS/2 and PC-DOS.  Interestingly enough it is not physically possible to read a XDF formatted floppy under Windows at all, so we only support the use of XDF floppy disk images (not physical disks).

You may come across floppy disk images that are already in these formats, in which case they will just work.  Or you can make your own floppy disk images in these formats by using tools like WinImage (https://www.winimage.com).

Cheers,
Ben

Comments

  • Anonymous
    January 04, 2007
    The comment has been removed

  • Anonymous
    January 04, 2007
    360 KB floppy disks were 5.25" in size, and I used them on the PC (before 1.2 MB ones came along):  http://support.microsoft.com/kb/309623

  • Anonymous
    January 04, 2007
    The comment has been removed

  • Anonymous
    January 04, 2007
    >Anyway, the QX-11 also came with either one or two 360KB 3-1/4" single-density floppy drives. I meant 3-1/2", of course. Sorry! (Now that I think about it, the charting might have been separate from the spreadsheet. Some of the other details might also be a bit off since I haven't used the machine in 15 years)

  • Anonymous
    January 04, 2007
    Pretty sure the DMF format started with Win95.

  • Anonymous
    January 05, 2007
    360K format would most like really be the low-density 5.25" floppy that shipped with the original PC (1981). The original 3.5" Mac format floppies were 400K (not 360K) and used GCR encoding [1].  This encoding scheme can not be read by the floppy controller chip used in almost all PCs.  PC floppies (and the Trash-80) use MFM encoding. According to the Wikipedia article [2] on "floppy disk", there is no 3.5" 360K format.  There was, however, a 3" disk that held 360K, but it was not widely used in the USA. [1] http://en.wikipedia.org/wiki/Group_Code_Recording [2] http://en.wikipedia.org/wiki/Floppy_disks

  • Anonymous
    January 05, 2007
    >According to the Wikipedia article [2] on "floppy disk", there is no 3.5" 360K format. That's sort-of correct; as far as I know, there were no disks sold with those specs. The QX-11 used ordinary 720KB floppies. My understanding is that the drive skipped the odd-numbered tracks (so it used tracks 0, 2, 4, ... 78) for a total of 40 tracks and 9 sectors/track = 360KB.

  • Anonymous
    January 05, 2007
    I think there was a version of Office2000 on DMF disks - lots of them. Windows Installer (MSI) was specifically built to handle this kind of many-disk distribution, hence its strange handling of media, and reliance on volume labels.

  • Anonymous
    January 05, 2007
    Actually, most 5.25" floppy disks were formatted to 320kb (8 tracks) not 360kb (9 tracks) because earlier versions of DOS cannot handle the 9 track format (this is mentioned in the Wikipedia article). You are correct that the Macintosh floppies were formatted to 400kb - so maybe our low density format is just a nonstandard 5.25". RE: DMF - it was used for floppy installs of Windows 95, but it was also used long before then. Cheers, Ben

  • Anonymous
    January 05, 2007
    The comment has been removed

  • Anonymous
    January 07, 2007
    Seems that at present no virtualization software support 5.25" 160kb or 180kb single-sided disk images.

  • Anonymous
    January 09, 2007
    If anyone on here has seen my virtual 5 1/4" floppy disk notcher, please let me know.  I seen to have misplaced it the last time I was on here, and I need to virtually double the size of my virtual floppy.  ;) I'm suddenly having flashbacks to my TRASH 80 model 1, and I blame all of you for that!  If I can't sleep tonight, I know who to blame. Did someone say Amiga?  Ah, happy thoughts. Great discussion guys!

  • Anonymous
    January 19, 2007
    >> If anyone on here has seen my virtual 5 1/4" floppy disk notcher, please let me know. << I've got it right here:  attrib -r floppy.img

  • Anonymous
    December 26, 2010
    The comment has been removed

  • Anonymous
    June 03, 2011
    What about the 320K diskettes of DOS 1.0 and 1.1?

  • Anonymous
    October 27, 2013
    DOS 1.0 supports only 160k diskettes, not 320k, but anyway, all these 160k/180k/320k floppy images lying around can easily be converted to 360k images and used in VirtualPC 2007/Win7.