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Top Document: Atari 8-Bit Computers: Frequently Asked Questions
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Next Document: 11.3) Can I read/write MS-DOS disks on an 8-bit Atari?

11.2) Can I read/write 8-bit Atari disks on an IBM-PC?

There are several programs that allow an MS-DOS system to work with an
Atari-format diskette.  The following require a DOS and disk drive on the
Atari end capable of the SS/DD 180K format:

ATARIO by Dave Brandman w/ Kevin White - Reads SS/DD 180K Atari disks.
  filename: Diskutils/atario21.arc

SpartaRead by Oscar Fowler - Reads SS/DD 180K SpartaDOS disks.
  filename: Diskutils/sr.arc

UTIL by Charles Marslett - Reads/Writes SS/DD 180K Atari disks. Use MyUTIL!
  filename: Diskutils/dskutil.arc
     (Older versions are contained in pcxfer.arc, util.arc, and ataridsk.arc)

MyUTIL by Charles Marslett with Mark Vallevand, and
SpartaDOS disk utility by Mark Vallevand
  filename: Diskutils/myutil.zip
     includes best version of UTIL for read/write of SS/DD 180K Atari disks,
     plus Mark's SpartaDOS disk utility v0.1e to access 180K SpartaDOS disks

MyUTIL and the XF551 - tips from mailto:JTKIRK@urp.edu.pe:

]MyUtil works fine with the XF551. The XF551's speed is 300 rpm (sometimes even
]up to 303 rpm). I've got two XF551s and can read/write disks written on a PC
]with MyUtil on both with no problems. MyUtil even can write to a DS/DD disk,
]for a total of 360 K, BUT: the ATARI disks not only have the bits inverted,
]the second side is also read BACKWARDS respect to PC disks. That is, when
]MyUtil on the PC writes to what it thinks is sector 721, it really is writing
]to sector 1440! Worse, if you take an ATARI disk with a file whose sectors
]get past sector 720, MyUtil will attempt to read the sector 2161-n instead of
]'n', and you'll get a 'truncated record' error. The solution is simply to
]rewrite the code to take into account this (if sec>720 then sec=2161-sec).
]Let me know if you modify this. You don't know how frustrating it is to have
]to use only 180 K of a 360 K disk! I'm going to analyze the source code, but
]I don't know if I will be able to modify it properly. If someone does it
]before, please email me and send me an uuencoded copy or tell me where to get
]it.

Here's some advice on using the above utilities from mailto:hans@umd5.umd.edu
(Hans Breitenlohner):

There are two technical obstacles to interchanging disks between
DD Atari drives and PC drives.

1. The Atari drive spins slightly slower (288 rpm instead of 300 rpm).
   If you format a disk on the Atari, then write sectors on the PC, it is
   possible that the header of the next physical sector will be overwritten,
   making that sector unreadable.  (The next physical sector is usually
   the current logical sector+2).  The solution to this is to format all
   disks on the PC.
       (Aside:  Does anybody know how this problem is handled on the
        XF551?  Is it also slowed down?)
     Konrad Kokoszkiewicz, mailto:draco@mi.com.pl answers:
     "The XF551 disk drive is not slowed down - these drives are spinning
     300 rotations per minute. To prevent troubles with read/write disks
     formatted and written on normal Atari drives (288 rot/min), the main
     crystal frequency for the floppy disk controller is 8.333 MHz
     (not 8 MHz, as in 1050, for example)."

2. If the PC drive is a 1.2M drive there is the additional problem of the
   track width.  The following is generally true in the PC world:
    - disks written on 360k drives can be read on either drive
    - blank disk formatted and written on 1.2M drives can be read on
      either kind
    - disks written on a 360k drive, and overwritten on a 1.2M drive,
      can be read reliably only on a 1.2M drive.
    - disks previously formatted on a 360k drive, or formatted as 1.2MB,
      and then reformatted on a 1.2M drive to 360k, can be read reliably
      only on a 1.2M drive.
    (all this assumes you are using DD media, not HD).

   Solution: Use a 360k drive if you can.  If not, format disks on the
   Atari for Atari to PC transfers, format truly blank disks on the PC
   for PC to Atari transfers.

   Jon D. Melbo, mailto:ssilicon@lax.net sums it up this way:
   So a basic rule of themb when sharing 360KB floppies among 360KB &
   1.2MB drives is: Never do any writes with a 1.2MB drive to a disk that
   has been previously written to in a 360KB drive....UNLESS... you only
   plan on ever using that disk in the 1.2Mb drive from then on out. Of
   course a disk can be reformated in a particular drive any time for use
   in that drive.   As long as you follow that rule, you can utilize the
   backwards compatible 360KB modes that most 1.2MB drives offer.


While the above work with SS/DD 180K Atari-format disks, the following
combination of utilities can be used to work with SS/SD 90K Atari-format
disks, and is currently the best bet for reading SS/ED 128K Atari-format
disks.

AnaDisk 2.07, shareware by Sydex - Reads/Writes "any" 5.25" diskette
  filenames: Xf2/anad207.zip, Xf2/anadisk.txt
Deana by Nate Monson - converts AnaDisk dump files from Atari format
  filenames: Xf2/deana.com, Xf2/deana.txt

Explanation --> According to mailto:crow@cs.dartmouth.edu (Preston Crow),
"As best as I can figure it out, if your PC drive happens to read
FM disks (I'm not sure what the criteria for that is), then you
can read single density disks on your PC by dumping the contents
to a file with AnaDisk, and then using Deana.com to convert the
dump file into a usable format.
For enhanced density disks, Anadisk generally only reads the first
portion of each sector, but it demonstrates that it is possible for
a PC drive to read enhanced density disks."