20 Aug
2015
20 Aug
'15
8:01 p.m.
Date: Thu, 20 Aug 2015 13:57:05 -0700
From: cclist at sydex.com
To: General at classiccmp.org; classiccmp.org:On-Topic and Off-Topic Posts cctalk at
classiccmp.org
Subject: Re: 5.25 floppies that read but don't write
On 08/20/2015 01:04 PM, Marc Verdiell wrote:
If formatting an already formatted disk, the format program will notlet you format
a different density.Do note what I said earlier. Just formatting and writing to a 360K ona
1.2M drive can in some cases make it unusable on a 360K drive.The 1.2M drive does not
erase the full width of a 360K track.When attempting to read on a 360K drive, there will
be too much noisefrom the older track.If you are really interested in creating 360K disk,
you must have a 360Kdrive.Dwight
So I tried to force formatting in DOS at 360k,
and sure enough it
worked! I can then read the diskette back, write on it, etc... And of
course it failed formatting at 1.2 Mb. But the drive (Chinon FR-506)
is a 1.2M one, and reads fine at 1.2M! Any clue? Is there a drive
setting that would prevent it to write at high density but let it do
at low density?
At high density, have you taken a good look at pin 2 of the floppy
interface? Have you checked to see if pin 2 is configured (via jumpers)
as "density select"? Various drives have different jumperings for
pins 2 and 34 (and sometimes 4). For example, I deal with some Japanese
CNC gear that uses pin 2 for disk change and pin 34 for read (and pin 4
for "in use".
--Chuck