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Great Hierophant
September 7th, 2011, 06:41 PM
I tracked down a program called Testdrive by Microsystems Development, hoping to run a full diagnostic check on all my double density floppy drives. While it can do a basic read/write test and rotational speed test, the rest of the tests require a Dysan Diagnostics Diskette. Dysan went out of business sometime in the late 80s or early 90s, and I assume their diagnostic floppy was not something you could take an image of or duplicate with standard PC floppies. A company called Accurite advertises products that can diagnose drive issues. Are there other programs or sources for the diagnostic diskettes?

Chuck(G)
September 7th, 2011, 07:00 PM
You're right; the diagnostic floppies are custom-made on special rigs. And there are two types: so-called "digital" and "analog" alignment disks. The analog models were made to be used with an oscilloscope on the read channel output; any attached computer (not strictly necessary) was used just to step the positioner in or out.

The digital alignment disks record sort of a spiral off-center pattern and use the computer to handle things. Depending on what's read, the PC can determine how far off the alignment of the floppy is.

I tend to use the digital ones with a program called "AlignIt"--it seems to be much faster and just as accurate as the analog ones (I've got those too) and a whole lot less trouble. I can check the alignment of a drive without removing it from the PC. Not so with AAD.

But digital alignment disks are all different, so make sure that the one from Accurite comes with its own software or the disk is compatible with the package you intend to use.

Now, it might be possible to make these yourself if you have a drive that can vary the position from center-of track while recording. I suppose for small displacements you could also format a track and then write a sector, bump the alignment, write the next sector and so on.

For 5.25" floppies a Drivetek drive would be perfect for this sort of thing because it has two positioner motors; "coarse" and "fine" ones.

You could also mount a drive on a plate and drive the positioner shaft through an external stepper connected to a backlash-free reduction drive. That would allow you to change head position by very small amounts.