🚀 go-pugleaf

I've had good luck writing 360K disks on several varieties of 96TPI
drives including 1.2 Mb drives on an AT, 800K drives on an Eagle 1620
and others.  The normal difficulty seems to be that the write heads
on the 96TPI drives is only half as wide and so when used in the
360K mode only reads and writes half the track used by the normal
360K drives.  This means that reading is never a problem, but when
you write it only changes the information on half of the track.  If
read back on a 96TPI drive there is no problem (since it only reads
the half anyway), but when read on a normal 360K drive the wider
head sees conflicting data on the two halves of the track and
concludes that the disk is not formatted.  
  
There seems to be no way to write both halves of the track with the
narrow heads and keep them aligned accurately enough to read back
correctly on 360K disk UNLESS the other half is BLANK.  The solution
I've used without a failure is to use virgin disks (ones never
formatted).  Format them on the 1.2M drive requesting the 360k
density.  This means that the other half of each track is not even
formatted (random magnetic patterns).  Then write whatever is
desired on the disk.  It may now be read on a 360K drive. BUT NEVER
WRITE TO IT USING A 360 K DRIVE.  If you ever write to it the other
half track will get used and the 1.2M drive will never be able to
change that half.  The totally unformatted half has such a weak
magnetic signal that it causes no problem.

Thus you need different disks to copy back and forth, esp in the
1.2M to 360K direction.  You have to keep a special disk never
written to by a 360K drive just to use for transferring.  This is a
small nuisance but seems to work everytime.  I have considered
trying to use disks that have been demagnetized by a bulk tape
demagnetizer to see if they work but have never done it.

			-- Terry L Anderson
			   AT&T Bell Laboratories - Liberty Corners
			   ...!ihnp4!daimler!kaiser!tla

In article <1986Oct26.184138.24015@utcsstat.uucp> spence@utcsstat.UUCP writes:
>
>I'd appreciate hearing from anyone who has used CPYAT2PC (or any similar
>program).  I use an AT as well as several PCs.  The AT has a 1.2 Mb drive 
>in addition to its hard disk.  I don't want to add a 360K drive, but I do
>want to be able to write 360K diskettes as well as read them.
>
>Does CPYAT2PC really do the job?  Are there other solutions? 
>
>Ian Spence {allegra,decvax,ihnp4,seismo,watmath}!utcs!utcsstat!spence


Hi,

To quote the IBM PC-DOS Manual for version 3.10, concerning FORMAT.COM:

/4 to format a double sided diskette in a high capcity drive. pg. 7-107

Which means that by entering the command 'FORMAT A: /4<cr>' you may
format a 360K diskette in a 1.2M disk drive.

The manual does mention that this technique is not 100% reliable, and that
some 360K disk drives may not be able to read the diskettes formatted in 
this fashion. I guess it has to do with drive calibration, as I have not
had any problems taking diskettes formatted in my AT to my Deskpro at home,
or to any other IBM PC.

Good Luck all....

-- 
Tim Margeson (206)253-5240
PO Box 3500  d/s C1-937                          @@   'Who said that?'  
Vancouver, WA. 98668
{allegra..inhp4..decvax..ucbvax}!tektronix!tekigm2!timothym