[Offer] Quarterdeck Desq 1.0 (SCP)

This version is copy protected (Starter disk), for which I include 2 dumps using SCP. The seal of the disk was broken so I cannot guarantee it has not been modified. The other 3 disks were still sealed therefore untouched.



  • Thanks a lot. We have one dump out there, but it is missing the protected bits.
  • edited January 5
    Thanks, unfortunately DESQ directory is generated on Disk 1.
    But I recovered (restored) it perfectly.
    I'm testing to install on HDD with IBM PC DOS 3.30

    To install it on HDD, you should run it as follows.


    I added screenshot. You can refer the URL.


    Quarterdesk Desq 1.0 - Starter disk [5.25]-2.scp has bad sector on Track 38/1/1, but no problem because it is unused area. (blank area)

  • @ibmpc5150 thanks for the fix! For installation the manuals says you have to be on root of c: and type a:install.
    It will create directories automatically.
    Concerning the bad sector, is it not a feature of the copy protection scheme?
  • I would not worry about this too much, but all of the disk dumps show noise on the last few tracks. This is not copy protection, but rather some issue with the disks or drive. If you view the images in HxC you can visibly see red on green splotches, indicating decoding problems. (ignore red on black)

    That indicates some kind of noise in the signal. That indicates that the flux-MFM decoding algorithm is not quite sure if the decoded bits are correct. Since the sectors are shown as green, by chance the MFM-data decoding has succeeded and the data is valid.

    On IBM PC style copy protections, protected tracks are almost always written with perfectly valid signals and MFM encoding. Instead, the contents of the MFM are intentionally altered, usually creating things like odd sized sectors, hidden data, or overlapping sectors.

    In this case, note the track that is mostly orange. That is the protected track. There are no red bits in it, indicating that the MFM has read and decoded properly. Orange indicates that the sector CRC is incorrect. Since there are no red bits indicating any kind of read error, we can conclude that these sector "errors" are intentional.

    At a glance, the protection type seems to consist of intentionally overlapping and invalid sectors.

    By chance, HxC can decode all of the sectors, so we can "reconstitute" the image if needed, but ideally the problems would be identified, corrected, and the images re-dumped.

    The primary reason is that writing the SCP images "as is" would not create a fully usable image. Although we can read this copy, imagine making a photocopy of a photocopy - with added noise, that copy won't be quite readable.

    The secondary reason is that different tools with different flux decoding algorithms, such as the PCE flux tools, may fail to decode the sector data.

    Unfortunately, the cause could be one of a number of things:
    -Dirty heads, Try using a head cleaner and try again.
    -Minor drive alignment/filtering - try a different drive
    -Disk damage - inspect the disks to see if scratches have appeared on the surface.
    -Residue - residue may not be visible. Either careful cleaning with a q-tip or just running the disk through the dump process 5 or 6 times might improve things.
    -Mastering problem - the disk was WRITTEN with noise on it, in which case there is not much you can do.

    What I would do: Inspect the disks for any damage or residue (since they were unused, I'm guessing that there is little or none), run a head cleaner in the drive, then just try re-dumping a few more times and see if anything changes. However, I have a hunch this may be a mastering problem, so it may not change.

    But as I said, you got what we need off of the disks, so I would not worry about this too much.
  • thanks for this comprehensive answer, always good to learn new things.
  • I added a scan of the manual and papers that were in the box. The full archive is updated here : https://mega.nz/file/OGh3kQ5T#nuw7ePaCLwi66GVfzV7nBXqDZ5ElRiU2f64Sw-d4ZpI
  • Here is restored (fix) image of disk 1.
    It may be same as original default.

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