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From: apratt@atari.UUcp (Allan Pratt)
Newsgroups: comp.sys.atari.st
Subject: Re: A challenge to you disk experts
Message-ID: <492@atari.UUcp>
Date: Fri, 19-Dec-86 13:49:19 EST
Article-I.D.: atari.492
Posted: Fri Dec 19 13:49:19 1986
Date-Received: Sat, 20-Dec-86 06:15:58 EST
References: <1866@batcomputer.tn.cornell.edu>
Organization: Atari Corp., Sunnyvale CA
Lines: 42

Moshe Braner asks about single- and double-sided disks.

You could make one physical DS disk into two logical SS disks by
writing a device driver for a DS floppy disk drive which would treat
one surface as one logical SS disk, and the other surface as another
logical SS disk.  This would involve linking in to the RWABS vector
(like RAMDISKs do) and translating the device and logical record
numbers for your two logical devices (M: and N: or whatever) into
less-logical record numbers for the physical device (A:).

You can also post-process an SS disk to make it a DS disk without
copying the original information: you would have to write a device
driver which modified the current DS logical record sequence (head 0,
then head 1, then on to the next track) into a new one: track 0-79 on
head 0, then tracks 79-0 on head 1.  That way the existing data on an
SS disk would not have to be moved at all.  The information on the
boot sector would have to be modified to reflect all the new tracks
you're getting, and Side 1 would have to be formatted, but otherwise
nothing changes: the FATs are the same size for SS and DS.

Note that in neither case will the normal desktop format/copy routines
work, not only because these disk formats are "foreign" to it, but
because it checks explicitly for drive identifiers A and B.  Ever
notice that you can't copy a 360K RAMDISK to a floppy, except
file-by-file?  Same reasons.

Having said all this, I think it all doesn't matter anyway: it doesn't
take THAT long to copy an SS disk file by file.  You can just go get a
cup of coffee, or read a book, while the copy is taking place.  If you
have one drive, of course, you want to get a RAMdisk, so you can copy
(file by file) from the original to RAM, then from RAM to the backup.

Does everybody know that you can copy ALL the files on one disk to
another, without selecting the files?  If you want to copy B to A file
by file, you can open A (the destination), then drag the icon for B
into the open window for A.  This will copy all the files, one at a
time, including (of course) the directory structure.

/----------------------------------------------\
| Opinions expressed above do not necessarily  |  -- Allan Pratt, Atari Corp.
| reflect those of Atari Corp. or anyone else. |     ...lll-lcc!atari!apratt
\----------------------------------------------/