Subj : Re: floppy disks
To   : StormTrooper
From : boraxman
Date : Wed Apr 30 2025 01:09 am

On 29 Apr 2025 at 02:48a, StormTrooper pondered and said...
 
 St>  bo> What was interesting about floppies was they could be formatted to
 St>  bo> different capacities.  There was this DOS program called 2M that was
 St>  bo> pretty cool that let you format disks to greater capacities, by putti
 St>  bo> more sectors per tracks, and more tracks.  You could get over 800K on
 St>  bo> 5 1/4" DS/DD diskette, and up to 1.8M on the 1.44 M disks.
 St> 
 St> The Apple II world had something similar.  DOS 3.3 nominally wrote 35
 St> tracks per disk side.  Even straight out of the factory you could
 St> generally get at least an extra 2 tracks onto the disk.  In some cases
 St> as many as 4.  Only trouble was it wasn't reliable across the board.  If
 St> you only wrote 1 or 2 extra tracks you'd be reasonably sure anyone could
 St> use it, but you'd come across drives that could only do 35 and then it'd
 St> be useless. Above that was even worse, basically just tailored to your
 St> own personal setup. You also had to patch DOS to do it, no biggy it was
 St> just a poke once it was loaded, but std DOS couldn't see the extra
 St> tracks even though they'd be referenced in the directory.
 St> 

I was in possession of an Amstrad PC2386 for a few years.  That machine could format, by default, a 720K 3.5" DD disk to 1.44M HD.  Apparently it could be done, if you punched a hole in it, in the corner, but the drive in this Amstrad at least, didn't need the hole.  I guess it lacked the sensor to see if the hole was there or not, and just treated it as a 1.44M disk.

Later, when I wanted to read the disks on another machine, I had to drill the holes in.

Oddly, despite them not really supporting that data density, they were reliable for years.  Must have been high quality disks.

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