MS-DOS 3.20 (Zenith PC OEM, 3.5in 720k) not working with Zenith ZFL-181-92

Hey folks,
I’ve got a Zenith laptop (model in thread title) that came with an MS-DOS 2.11 end user demo disk. That works fine. I wanted a more updated (and the full version) of DOS, so I downloaded 3.20 from this site. The issue is that the computer (for whatever reason) refuses to read the operating disk upon startup. If I put it in the B drive, I can access the directory for the 3.20 disk, but it won’t launch in the A drive (startup drive). Would anyone be able to help me with this?

Thanks in advance!


  • How did you write the disk image to your floppy disk?

  • I downloaded it as a zip file, unpacked it, and then copied everything straight to the disk. I used a USB floppy drive, if that helps any.

  • That won’t work. You need to use special software to write the image. I like winimage.

  • Also, the files you're writing seem to be fore 720k floppy disks and some USB drives do not like 720k floppies.

  • The drive I have is a 720k and 1.4 Mb drive. To my knowledge, it wrote everything fine. And you said Winimage. Is that free?

  • If you had bothered to search with your internet search engine of choice, you would have seen it is shareware, and it can be downloaded here:

    As mentioned, just copying files from within an image will not write the boot sector needed to boot a system disk. You need a tool like Winimage to easily make a system disk.

    There are other similar programs but this is the one we recommend for writing disk images in Windows. Note that if you READ disks using Winimage, you should remember to write protect your disks, as Windows can write stuff without your knowledge.

  • edited June 2020

    Forgive me that my query was not to your satisfaction, but at the time of writing, I was engaged in another task (fixing my Grandmother’s Digital to Analog converter box) that required the vast majority of my attention until completed, so I could only spare enough time to simply ask the question in the forum, as opposed to looking it up myself.

    Thanks for the heads up on the write protect, I’ll make sure to engage the protection cover.

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