Formatting a 3.5" HD diskette to 720K - broken?

Formatting a 3.5" HD diskette to 720K - broken?

Post by David J Birnba » Sat, 14 Nov 1992 04:53:27



Apologies for my recent OS/2 posting. I forgot which group I was
reading.

--David

--


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Pittsburgh, PA  15123  USA          fax:   1-412-624-9714

 
 
 

Formatting a 3.5" HD diskette to 720K - broken?

Post by David J Birnba » Sat, 14 Nov 1992 04:50:31


I thought I'd never want to format a 720K 3.5" diskette again, but I'm
trying to use diskcopy to back up some software distributed in that
format. OS/2 refuses to comply. I'm using a HD diskette that OS/2 was
happy to format at 1.44K. I wiped that formatting clean with a bulk
eraser before trying to reformat at lower density. The results:

1) If I click on the drive icon, select format, and set the density to
720K, the first 50% goes smoothly. The drive then begins to chug. After
several seconds, the bar grudging slips a little beyond 50%. The drive
then chugs forever, making no progress, until I abort.

2) If I use an OS/2 window and type 'format a: /n:9' (following
instructions), the first 50% goes smoothly, then the chugging starts,
then we creep up to 56%, and there we chug until I abort.

3) If I use a DOS window and the appropriate parameters, the formatting
reaches 100% and then apports with a "DMA across 64K" error message.
Selecting 'retry' doesn't help. The disk is unreadable when I abort the
format.

4) If I use a DOS window and run fdformat version 1.8 with the /f:720
option (normal 720K format, with no funny stuff), I get the same error
message as in #3. Using the /A (BIOS) option doesn't help.

All of the above are reproducible and were tried with multiple diskettes
(which, as I mentioned, were easily formatted to 14.4K).

Anyone know what gives?

Thanks,

David

--


3955 Bigelow Boulevard              voice: 1-412-687-4653
Pittsburgh, PA  15123  USA          fax:   1-412-624-9714

 
 
 

Formatting a 3.5" HD diskette to 720K - broken?

Post by GNR.. » Sun, 15 Nov 1992 06:28:08


       as long as the question is raised, how do you do it in MSDOS?

                                   Gordon Rogers

 
 
 

Formatting a 3.5" HD diskette to 720K - broken?

Post by Jaap Verha » Wed, 18 Nov 1992 04:12:14



>       as long as the question is raised, how do you do it in MSDOS?
>                                   Gordon Rogers


DOS 5: FORMAT <drive:> /F:720 /U <Return>

and don't forget the /U (for `unconditional').
--
Regards, Jaap.

Jaap Verhage, Academic Computer Centre, Utrecht University, Holland.

 
 
 

Formatting a 3.5" HD diskette to 720K - broken?

Post by Sharon Snyd » Thu, 19 Nov 1992 04:18:09


To format a 3.5 HD disk as DD (720k) cover up the extra hole (not
the write protect stuff) and format it as 720K (I forget the
command line right now).  It should work.

Sharon Snyder


 
 
 

Formatting a 3.5" HD diskette to 720K - broken?

Post by robert.k.nicho » Thu, 19 Nov 1992 12:48:57



>To format a 3.5 HD disk as DD (720k) cover up the extra hole (not
>the write protect stuff) and format it as 720K (I forget the
>command line right now).  It should work.

...

It will sort-of work.  The problem is, the drive will be using the
reduced write current suitable for the magnetic coating on a real DD
diskette, and not the higher current required for reliable writing on
the magnetically "harder" media of the HD diskette that you are using.

(The disaster potential is not quite as insideous here as it is for
people who try to get cheap HD disks by punching the extra hole.  They
have to contend with data that will decay away over time (6 months to a
year, perhaps).  Taping over the hole in a HD diskette will just cause
somewhat marginal writes -- whatever data actually makes it onto the
disk should be stable.)

Bob Nichols
AT&T Bell Laboratories

 
 
 

Formatting a 3.5" HD diskette to 720K - broken?

Post by Paul Duckl » Sat, 21 Nov 1992 16:21:25


Quote:>To format a 3.5 HD disk as DD (720k) cover up the extra hole (not
>the write protect stuff) and format it as 720K (I forget the
>command line right now).  It should work.

You don't need to cover the hole. The hole's there, as I understand
it, to stop you formatting a 720KB disc to 1.44MB. Of course, some
claim that the hole is used to create two market entries from a single
type of disc. I gather, though, that the coercivities of 720KB and
1.44MB *are* different -- but close enough that you *can* format a
720 disc to 1.44, albeit with lower reliability.

Just tell FORMAT which disc format you want. DR-DOS 6.0 lets you
specify /F:720 to achieve the desired result.

[No such "hole" was needed to allow the hardware to distinguish 360
 from 1.2 floppies, because the difference in coercivity of these discs
 is such that a 360 disc will bomb out pretty immediately when you try
 to format it to 1.2MB]

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1. Formatting 3.5" DD disc in 3.5" HD floppy drive

Hi,

I've got problems formatting 3.5" DD disks in a 3.5" HD floppy drive. I use BIOS
int 13h, function 05h to format each track of the disk. The BIOS call does not
return any errors, but after the format process, I can't write onto the disk (to
create boot sector etc.) without errors. The errors reported by the write
function differ from the disk I use. There's a disk on which I can write each
sector of any track except the last, 9th. Another disk, the write function
reports error code 02h (address mark not found) for every sector.

Any suggestions on that?

BTW, is it possible to format a 5.25" HD disk in a 5.25" HD floppy drive for
less than 1.2MB? I failed even with DOS Format formatting for i.g. 360k.

Any answer will be appreciated,

Thomas

 * Origin: OASE - European Shareware Authors Organization, info: (2:246/1803.7)

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