Virtual PC and Floppy Images

I use Virtual PC for Mac to run Windows 2000 on my Powerbook. I had some 3.5″ floppy disk images from an MSDN disk that I wanted to use, but Virtual PC didn’t like them. I figured out why.

The floppy disks images need to be named with either .vfd or .dmg extensions. But, more importantly, they need to be the right size. They need to be exactly 1474560 bytes in size. The particular files I got off my MSDN CD-ROM were not exactly that size. Obviously whatever disk image creation software Microsoft used didn’t bother to store a whole lot of zeros at the end of the floppy disk image. It only stored the data.

Using a command prompt, here’s how I created the proper size floppy disk image. I’m just concatenating a bunch of zeroes on the end of the existing image.

  1. Find out how many zeros you need. Subtract the size of the disk image from 1474560. I did that this way:
    echo '1474560 - 1424460' | bc

    The answer is printed out (50100 in this case).

  2. Create a file with that many zeroes in it. I did it this way:
    dd if=/dev/zero of=padding bs=50100 count=1

    That creates a file named padding that is exactly 50100 bytes of zeroes.

  3. Concatenate them. thus:
    cat originalImageFile padding > diskImage.dmg

Now I put that file in my Virtual PC folder. (~/Documents/Virtual PC Lists for me). I can capture them and use them now.


  1. Steve

    after searching google for disk images for virtual pc i came across this. You seem to know abit about it so where could I get some disk images so I can run windows on my virtual pc.


  2. Paco Hope

    If you want to run Windows on your Virtual PC, you need a valid and legal license. Any CD that you buy from any store will work. I have, for example, a Windows Me CD that I used to use on an old PC. I decommissioned the PC (it runs OpenBSD now) and now I use that license in Virtual PC. Just insert the CD in your CD drive and start up a new Virtual PC. It will boot from the CD and you’re off to the races.

    If you want images so that you don’t have to buy windows, you’re trying to break the law. I don’t support that. Go look for warez sites where people routinely break the law.

  3. Matt

    I have a retail copy of Virtual PC 7 for Mac. Program installed fine, but it will not load from my copy of Windows ME. Keeps saying no OS installed. Talked with Microsoft. They said download a startup floppy image from the web. Did that. Used VPC to create virtual floppy drive. Attached it. Now, when VPC starts, to try to install, it says, “No System Disk or bad disk” something to that effect. Is there any legal image that will start my system up? I’ve got licensed copies of VPC 7 and Windows ME, but can’t get VPC to install it?

  4. Wow, I stumbled across this looking for the proper name for floppies – to make it accept them. It didn’t like .img, and I was getting annoyed.

    Matt, if you’re still looking (after, oh, six months), try ejecting any floppy or CDs (or images). If you are really quick, you can hit ‘F1’ to get into MrBIOS. I do not believe that it actually saves settings, but there is a possibility that it may have become confused – or corrupt somehow.

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