dsc@drutx.UUCP (DavisCS) (08/11/86)
Would someone please provide some enlightenment - Just recently I began working with a 6300+ with a 1.2Mb drive. Knowing that the drive also had 360kb capabilies I assumed that translated to UNIX=1.2Mb and MS-DOS=360kb. Now I see that I can format diskettes for either density for both OSs. When do I use which for what? And if I'm using the diskette copy option, how do I tell what density I'm copying from? A related issue - I have 48 TPI DS-DD diskettes and 96 TPI DS-DD diskettes. Are these only for 360kb operations and is the difference simply quality? What must I use when I write at 1.2Mb? Scott ihnp4!drutx!dsc
lowe@psuvax1.UUCP (Tom Lowe) (08/19/86)
The following is a memo that was given to AT&T Hotline consultants
regarding the use of 360KB floppy disks and 1.2MB drives:
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subject: Living with a mix of 1.2-MB and
360-KB floppy drives
Here is a summary of how to live with a mix of 360-KB and
1.2 MB flppy drives on MS-DOS machiens. "Getting Started
with Your AT&T Personal Computer 6300 PLUS" says (page 3-36)
"... if you must use a 360-KB diskette in the
1.2-MB drive (drive A), use it only for reading
information. After using the 1.2-MB drive to
write on a 360-KB diskette, the diskette can only
be used in 1.2-MB drives."
AT&T does not officially support writing a 360-KB diskette
in a 1.2-MB drive and then reading it in a 360-KB drive.
Many people find that it can be done with reasonable
reliability, though, subject to the guidelines given below.
These guidelines are for informational purposes only, and
AT&T takes no responsiblity for operations not supported in
PC6300 PLUS user documentation.
The 360-KB head is wider than the 1.2-MB head, so a 360-KB head
reading a track that has been written by a 360-KB drive
first and a 1.2-MB drive last will be reading a narrow track
of new data in the middle of a wider track of old garbage.
Therefore:
1.2-MB drives will normally read 360-KB diskettes with no
trouble, whether the diskettes were formatted and/or written
on a 360-KB drive or a 1.2-MB drive.
360-KB drives will normally read 360-KB diskettes that have
been formatted only on a 1.2-MB drive and written only on a
1.2-MB drive.
360-KB drives may have trouble reading diskettes that have
been formatted and/or written first on a 360-KB drive and
then on a 1.2-MB drive. If you are reading a floppy and get
an error message with "ABORT, RETRY, OR IGNORE." either
abort or retry. "IGNORE" defeats the error-checking
mechanism and can sprinkle garbage amidst your data. As
long as you don't "IGNORE", it does not hurt to try rading.
For best results, though, use VIRGIN or BULK ERASED
diskettes to take data from a 1.2-MB drive to a 360-KB
drive. It helps to use higher-than-minimum quality (i.e.,
96tpi certified rather than 48tpi certified) diskettes, too.
Format and write the diskettes only on 1.2-MB drives. In
short, the user should keep two types of 360-KB diskettes in
a mixed-drive environment:
Type 1 Type 2
Format and Read Format and Read
Write on on Write on on
1.2-MB only 1.2-MB 360-KB only 1.2-MB
or or
360-KB 360-KB
Microbridge Computers Int'l., Inc., 655 Sky Way, Suite 125,
San Carlos, CA 94070, (415)593-8777, sells an MS-DOS program
called "CPYAT2PC." which is supposed to let a 1.2-MB drive
write a 360-KB diskette that is always readable on a 360-KB
drive, even if it has been written by a 360-KB drive at some
time in the past. AT&T has not tested this program and has
no official or unofficial opinion on it. I would be
interested in hearing about customer experiences.
xxxxxxxx x. xxxxxxx
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I hope that answers some questions any of you may have.
If you have any comments on this or are still confused, send
me a note and I will get you an answer.
--Tom Lowe
ihnp4!psuvax1!lowe