[comp.sys.atari.st] ibm pc diskettes

freuden@gryphon.CTS.COM (Ralph Freudenberger) (08/26/88)

I am posting this article for a friend who is as ignorant about
the atari machine as I am...

Is there software available for the st that will write ibm/pc compatible
diskettes?

thanx in advance,

	freuden@gryphon.cts.com

apratt@atari.UUCP (Allan Pratt) (08/27/88)

In article <5914@gryphon.CTS.COM> freuden@gryphon.CTS.COM 
(Ralph Freudenberger) writes:
> I am posting this article for a friend who is as ignorant about
> the atari machine as I am...
> 
> Is there software available for the st that will write ibm/pc compatible
> diskettes?
> 
> thanx in advance,
> 
> 	freuden@gryphon.cts.com

The ST already uses IBM PC compatible disks.  The one restriction is
that the disks must be formatted on a PC, not on an ST.  That
restriction is lifted for the new ROMs coming soon to an ST near you
(officially called TOS 1.4). 

Be careful when using PC disks, though: if you use one PC-formatted disk
on an ST, then pop it out and insert another one, the ST will NOT
recognize the fact that a new disk is in the drive.  The way to be sure
that the ST figures this out is to put an ST-formatted disk in the drive
and access it (get a directory or something) between the two
PC-formatted disks. 

If you want to know why this is, read on:

GEMDOS, like all good operating systems, keeps information about a disk
in its private memory.  This information includes things like the sizes
of the various parts of the disk, and some of the most-recently used
information.  When you change from one disk to another, the OS has to
realize that its memory is out of date -- this is called "media change."

The OS detects that the media MIGHT HAVE changed when you pop the disk
out.  If you put the same disk back in, the OS will realize that and
it won't invalidate its memory about that disk.

The trick used is to check the SERIAL NUMBER of the disk.  The serial
number is a random 3-byte number written to the disk when it was
formatted.  The assumption is that it is highly unlikely that two disks
will have the same serial number, or if they do they will not be used
one after the other. 

Unfortunately, the IBM PC doesn't use this same system.  Disks formatted
on a PC all seem to have the same serial number, so the OS can't tell
them apart.  When you switch from one to another, the OS will merrily
decide that the same disk is in the drive after all. 

This business about serial numbers has NOT changed in the new TOS. 
However, the desktop has been changed: it has always been true that a
window is open on a drive, you can hit ESCAPE to redisplay the
directory.  Now, however, when you hit ESCAPE the Desktop *forces*
the OS to forget what it knew about the disk in the drive and
re-read everything.  It *forces* a media change.

As I said before, disks formatted with TOS 1.4 are totally IBM compatible,
and have the added feature of random serial numbers, so these problems
should become more rare.

============================================
Opinions expressed above do not necessarily	-- Allan Pratt, Atari Corp.
reflect those of Atari Corp. or anyone else.	  ...ames!atari!apratt

med@druhi.ATT.COM (Myron Drapal) (08/29/88)

In article <1133@atari.UUCP>, apratt@atari.UUCP (Allan Pratt) writes:
> In article <5914@gryphon.CTS.COM> freuden@gryphon.CTS.COM 
> (Ralph Freudenberger) writes:
> > I am posting this article for a friend who is as ignorant about
> > the atari machine as I am...
> > 
> > Is there software available for the st that will write ibm/pc compatible
> > diskettes?
> > 
> > thanx in advance,
> > 
> > 	freuden@gryphon.cts.com
> 
> The ST already uses IBM PC compatible disks.  The one restriction is
> that the disks must be formatted on a PC, not on an ST.  That
> restriction is lifted for the new ROMs coming soon to an ST near you
> (officially called TOS 1.4). 

Other stuff removed...

> 
> As I said before, disks formatted with TOS 1.4 are totally IBM compatible,
> and have the added feature of random serial numbers, so these problems
> should become more rare.
> 
> ============================================
> Opinions expressed above do not necessarily	-- Allan Pratt, Atari Corp.
> reflect those of Atari Corp. or anyone else.	  ...ames!atari!apratt


Well, Allan, I really hate to rain on your parade again, but this stuff
about the new format being compatible with the PC is just not true...
At least not in the BETA ROMS...  I have a disk formatted by the new
BETA ROMS, and though the PC just doesn't barf on it like the old format
used to (e.g. Sector not found), the PC does not like the root directory
at all.  CHKDSK reports "XXX clusters lost", where XXX is the number
of clusters used by the files.  In short, this still doesn't work.  I
suspect that this is just another problem relating to the boot sector,
but I haven't had the time to look at it yet.


I also have been able to determine that disks formatted on the PC
read/write properly with the BETA ROMs though, so all is not lost.
But it really isn't all that much better than before.


					Myron Drapal
					AT&T Bell Laboratories
					Denver
					att!druhi!med

apratt@atari.UUCP (Allan Pratt) (09/01/88)

In article <3451@druhi.ATT.COM> med@druhi.ATT.COM (Myron Drapal) writes:
> Well, Allan, I really hate to rain on your parade again, but this stuff
> about the new format being compatible with the PC is just not true...
> At least not in the BETA ROMS...

PLEASE DO NOT USE NEWS TO REPORT BUGS IN UNRELEASED ATARI PRODUCTS.
PLEASE DO NOT USE NEWS TO REPORT BUGS IN UNRELEASED ATARI PRODUCTS.
PLEASE DO NOT USE NEWS TO REPORT BUGS IN UNRELEASED ATARI PRODUCTS.
PLEASE DO NOT USE NEWS TO REPORT BUGS IN UNRELEASED ATARI PRODUCTS.

Am I making myself clear?

If you have a comment to make about Beta ROMs or any other unreleased
Atari product, use the appropriate communication channels: in this case,
send us an SPR.  If you don't know how to do that (for example, because
you copied the ROMs without copying the instructions for reporting about
them) you can mail us a letter.  We probably won't even prosecute
you or the official beta tester who let you copy the ROMs, because we
want the feedback.  This is not a legal opinion, but it would be my
recommendation.  But you do not get any goodwill by flaming us in
public about UNRELEASED products.

Please cut it out.

I post this in public because the offense was committed in public.  I am
also sending mail, because that is far less likely to be overlooked by
the intended recipient. 

============================================
Opinions expressed above do not necessarily	-- Allan Pratt, Atari Corp.
reflect those of Atari Corp. or anyone else.	  ...ames!atari!apratt

hase@netmbx.UUCP (Hartmut Semken) (09/02/88)

In article <5914@gryphon.CTS.COM> freuden@gryphon.CTS.COM (Ralph Freudenberger) writes:
>Is there software available for the st that will write ibm/pc compatible
>diskettes?

This is called GEMDOS and is located in the ST ROMs.

The builtin FORMATTER will format diskettes with a format, not known to
DOS 3.3 (or 3.2 or the like).
If you format the disk on the IBM and write to it on the ST, all will
work fine.

There rare some problems with the 40-cylinder (360k) disk drives
connected to the ST: the track-to-track time of these drives is about 6
msec, the ST assumes 3 msec. You can patch that wit ha simple POKE (or
the like).
Mabe Atari will make the system variables related to the external
hardware (like 5.25 inch disk drives) official?

hase
-- 
Hartmut Semken, Lupsteiner Weg 67, 1000 Berlin 37 hase@netmbx.UUCP
If there is something more important than my ego, I want it caught and shot,
NOW! (Zaphod Beeblebrox)