On Sun, 8 Feb 2009, Dan Gahlinger wrote: If this is like the Dysan Digital Diagnostic Diskette, then that image won't be useable for anybody else, although it might reveal a little bit about the drive that read the image. The Dysan Digital Diagnostic Diskette can not be duplicated with an unmodified drive, no matter what software or special controller you might use. (dd, rawcopy, option board, Match-Point, etc.) The way that it works is by having sectors that are NOT in "correct" position, and seeing which ones the drive can read. If sector #1 is recorded off-track a little too close to the center of the diskette; #2 is recorded a little off-track a little too far from the center of the diskette; #3 is a little MORE too close to the center of the diskette; #4 is a little MORE too far from the center of the diskette, etc. If you try to read the track with a drive that is perfectly aligned, you get SOME sectors, and then errors. If your drive gets more even numbered than odd numbered sectors, etc. then you know which direction it is out of alignment. That's how it tests radial alignment! Other aspects of alignment are done with other DEVIATIONS from "normal" recording. You can NOT produce that kind of diskette on an unmodified drive. An "image" of the diskette would not be usable. However, an image of the diskette could be useful for copying and studying the software (bootable?) on the diskette that analyzes the "weird" formatting. Or, maybe an OPTICAL image of the diskette made using magnetic recording "disclosure fluid". Actually, that would be VERY interesting. -- Grumpy Ol' Fred cisin at xenosoft.com

On Sun, 8 Feb 2009, Jules Richardson wrote: That's what a "normal" [analog] alignment disk is about. I was not able to get an adequate cats-eye display using an NLS215 scope, which took away my best excuse for having one. The Dysan Digital alignment disks were available in 5.25" and 8" versions, with or without software provided - after all, there were a lot of mutually incompatable computers to use them on. I've heard of, but never used a 3.5" digital alignment disk. The 3.25" alignment diskettes that I had were all analog, and a bunch had been reformatted. If you could make those alignment changes realtime under software control, then that would be one helluva tool for recovering data from damaged and/or misaligned diskettes! -- Grumpy Ol' Fred cisin at xenosoft.com

On Sun, 8 Feb 2009, Chuck Guzis wrote: cheap trick would be to just microstep the head positioner probably good to 1/4-1/8 of a track (if the leadscrew/band is that good) might need to approach from one side only because of leadscrew-nut backlash Peter Wallace

I always wondered about this in a way. I have a couple of 'alignment/test' disks for c64 drives, originals and copies. now as far as copies go, the drives were aligned perfectly, run through all tests, adjusted precisely, then made copies with those. so wouldn't that mean it was either 1) close enough or 2) the alignment of any other drive would only be to that drives setup, which was as precise as we could get? so in the end does it really matter all that much? Dan. _________________________________________________________________ How fun is this? IMing with Windows Live Messenger just got better. http://www.microsoft.com/windows/windowslive/messenger.aspx

Fred Cisin wrote: Fred, Fred. Jay might have created the server where we virtually exist, but it does no good to invoke His name. Some* even have claimed that He is dead. I prefer to think that He has endowed us with free will to exercise good judgment in our discussions here. Some are better endowed than others, to be sure. Although He may seem an indifferent creator, He gave up his only Sun** for us that we may live in PC. Abend. *Evan **Sparcstation 20

On Mon, 9 Feb 2009, Jim Battle wrote: That's what I get for taking Jay's name in vain. We should always follow his commandments (or George Carlin's THREE). -- Grumpy Ol' Fred cisin at xenosoft.com

On Mon, 9 Feb 2009, Dan Gahlinger wrote: As the drives get rarer, the tools for fixing them PROPERLY get proportionately scarcer. Most people who use alignment disks, not just "a disk written on a good drive" understand their importance, and they often outlive the populations of the drives. For example, I have some 8" and 3.25" alignment disks, even though I RARELY use those drives. The most important aspect of alignment tools are that they MUST exceed the accuracy of the intended result. That CAN be achieved without necessarily buying old-stock. New alignment disks CAN be made - the specs, knowledge, and even most of the tooling is still around; they are just no longer in mass production. True. I can get a car to track "acceptably" without major tooling. I can do automotive frame alignment with laser pointers, magnets, my measuring tools, and a 24 inch pipe wrench. I PREFER to use a good alignment rack, it reduces the amount of effort. I can get a drive to read/write/format "acceptably" without major tooling. I can do drive alignment with a good scope, disclosing fluid, my measuring tools, and a hammer. Alignment disks SIGNIFICANTLY reduce the amount of effort.

Analogue alignment disks exist (AFAIK) for all floppy drive siszes and demountale hard disks. I have a few, I'd likle to find the 8" and 3" (not 3.5") floppy ones though. But not at the 'new' price :-) They were all pretty much the same. You move the heads to the right cylinder and connect a 'scope to the outputs of the read amplifier. Trigger the 'scope off the index pulse and adjust the head position until the 2 lobes of the patter are the same size. The problem (for many people) is that you need a 'scope. I have a thing called a 'Microtest' which allows you to do a disk alignment using an _analogue_ aligment disk but no 'scope. It needs a PC (according to the manual, the minimum spec is 256K RAM, 1 serial port, any type of display adapter). The unit is a little box containing a microcontroller (8035 IIRC) and an ADC, which is linked to the serial port on the PCB. YOu cable the drive up to the PC as drive B: and run the speical software supplied. You select the drive type from a menu and it shows a diagram (drawn with IBM liue drawing characters) of the drive PCB showing where to connect 5 leads from the ADC box to the drive (IIRC these are the differential outputw of the read amplifier, ground, index pulse, and track 0 sensor). And then you put in the alignment disk and run through a seires of tests (motor speed, raidal alignment, track 0 sensor position, and so on). I find it works quite well. I've modified an old Amstrad PPC640 'laptop; to have a DC37 socket in place of the second floppy drive. I can then connect the drive under test to this,. plug in the Microtest and do the alignnmet. One tip. If you have a drive that's probably fairly well aligned but which you intend to dismantle, repair and then have to realign, mark the positions of the track 0 sensor, index sensor, hard posiitoner, etc before you remocve them. I've been known to step the hard to cylinder 0 on an exerciser (provided the drive still basically works) and measure the clearance etween the head carriage and the stop with feeler guages, for example). Then when you reassmble, put things back in as close to the original position as you can/ This will not be accurate enough to be properly aligned, but it will be near enough that you can detect the alignment pattern. Otherwise you can find youself moving the heads all over the place in an attempt to find even a trace of the pattern. I would be very interested to find that out :-) -tony