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Varsity Scripsit 5.25 Disk01.img cannot be read by WinImage

altracker9altracker9
edited August 2016 in Software
I recently downloaded Varsity Scripsit (https://winworldpc.com/product/varsity-scripsit) and came across a small anomaly.

The archive contains (3) 5.25" 360k and (1) 3.5" 720k disk images. All the images were read ok by WinImage 8.5 except for the 5.25" disk01.img, which would not read that image. The weird part is that disk01.img could be read by PCem10.1 and PCE.

So in PCem10.1, I did a diskcopy to a new image and that new image also could not be read by WinImage.

So I Xcopied all the files to a new image, and this image was readable by WinImage.

I am wondering if anyone else has observed this?

Comments

  • ibmpc5150ibmpc5150
    Boot sector (Track 0/0/1) of Disk 1 is filled F6h byte.
    It is impossible to recognize by Winimage.

    This is Winimage's issue not the disk 1's problem.
  • SomeGuySomeGuy
    The problem is the boot sector on that disk does not contain a valid Bios Parameter Block (BPB) that describes the disk geometry. WinImage requires that, however under genuine MS-DOS 160K/180K/320K/360K disks do not actually require a valid BPB.

    MS-DOS uses a different algorithm to determine the format because disks formatted with DOS 1.x do not use a BPB, and due to a bug many disks formatted with IBM PC-DOS 2.00 have incorrect data in the PBP.

    That is actually not the first disk I have come across that has a completely blank boot sector - that was actually a completely valid thing to do under most other OSes, and it just happened to "work" for 360k disks under real DOS.

    So due to the limitations in WinImage, it will not open these types of disks. And we have MANY of these kinds of disks on that site.

    It is kind of hard to be 100% sure, but this specific disk was probably mastered that way. I must not have noticed that or I would have also included an ImageDisk format file.

    In this case the software on the 720k disk is identical to the 360k disks, so if you just need the files, you can use those.

    If you need to write the 360k image to a genuine 360k disk, see this topic: viewtopic.php?t=6931 to convert them to ImageDisk format and use ImageDisk to write it instead. (Or in this case you could use a hex editor to copy the first 512 bytes from another 360k DOS disk image over the first 512 bytes of this image)
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