Re: Alignment disk and diagnostic program - ][+ and //e

[mjmahon@aol.com (Michael J. Mahon)]

>bill_h@sunsouthwest.com wrote:
>
>Michael J. Mahon wrote:
>> 
>> It is apparently worth saying again:
>> 
>> THERE IS NO WAY TO MAKE A USEFUL COPY OF A
>> HARDWARE ALIGNMENT DISKETTE BY USING AN APPLE DISK DRIVE.
>> 
>> The signals written to such a diskette are not digital signals.
>
>Well, the first statment is true. The second isn't.

Perhaps for some alignment disks, but a standard
"eye plot" alignment disk has two sine waves recorded,
each offset on opposite sides of the track center.
Alignment is adjusted by attaching an ocilloscope
to the read amplifier test point inside the drive, and
adjusting the head stepper by looking at the scope
pattern.

Evidently there are other (more modern?) alignment
disks, but the kind used to align Shugart 5.25" disks
was analog.  The scope pattern also clearly indicated
off-center clamping, worn/dirty heads, etc.



-michael

 Email:  mjmahon@aol.com
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