[sebhc] Floppies, archives, and ROMs

[Dwight K. Elvey]

>From: "Dave Dunfield" <dave04a at dunfield.com>
>
>At 11:26 02/02/2005 -0500, you wrote:
>>Can't the problem of detecting a new disk be solved by limiting the range of
>>the uController generating the "holes?" If the index holes get more than
>>+/-10 to 15% away from the 300RPM spec then the controller quits generating
>>holes. 
>>
---snip---
>
>(Since the drive motor is servo controlled, a disk that drags enough to slow
> it is going be a problem with or without this controller - I have a habit of
> watching the strobe disk of drives on the bench when they are active, and I
> have not seen drive speed variations with disks, except in extream cases
> where the disk was obviously defective]
>
>Regards,
>Dave

Hi
 I agree with Dave. When the disk is actually working, the
speed is almost right on the money. I often run my machines
with the covers off and can see the strobe disk on the
flywheels. With a drive that has been adjusted, I see
no difference in speed caused by disk loading unless it
actually causes the disk to have errors.
 I doubt that I've ever seen anything like a 10% error in
speed. Even a 1% error would show as a significant drift
on the strobe.
 As for disk with drag, I've found that one can grab the
center and manually rotate the disk a little to get it
moving smoothly again. This is especially nice to know
when it contains some old info you are looking for. If
you are willing to destroy the disk, you can always cut
the envelope open. For handling, it is always convenient
to have a smooth working envelope handy that you can slide
the bare disk into. It is usually best to have the opening
towards the door of the drive as the other edges are
used to located the disk.
Dwight


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