Re: High and Double density floppies

[valthoff@magnus.acs.ohio-state.edu (Victoria M Althoff)]

This doesn't make any sense to me at all.

The Disk ][ uses a completely-software method for finding sectors, so the 
timing hole is completely ignored.  So much for that theory.

My understanding is that the substrate of the high-density disks is exactly the
same as on double/single density disks.  In fact, the Disk ][ is quite happy 
with single density disks that no one has used (or been able to buy) for years.
 Okay, so if the substrate is the same, then print-through (cited by someone 
from AOL) should not be an issue.

Also, since the disk format is applied by the disk drive, differences between 
PC and Apple write format should not be an issue.

That leaves one of two possibilities:
a)  The high-density disk coating requires a higher magnetic flux to record
than the Disk ][ is capable of producing.  Given my experiences with 3.5" disk
drives (I have successfully formatted 1.44MB disks for 400k using the old Lisa
disk drive), I doubt that this is the case...especially since a high-flux
requirement would probably increase the probability of corrupting data on
adjacent tracks if the drive alignment isn't perfect.

or,

b)  No one has had the guts to try it.  In that case, break out your System 
Master, stick a 5.25"HD disk in the drive, and try INITing it  (hey...it's 
quicker and easier than using the ProDOS System Utilities...) and see what 
happens.  I see no reason why you shouldn't end up with a nice 143k 16-sector 
34-track 5.25" single-sided diskette!

(then, do the logical thing--cut the notch and flip it over!)

This reminds me of the early bullcrap about flipping disks over--claims that 
only one side had been certified--claims that were easily debunked by pointing 
out that some machines (i.e. CBM, Atari) put the R/W head on top, while others 
(Apple) put the head on the bottom...

--Dave Althoff, Jr.