Path: utzoo!attcan!uunet!ncrlnk!ncr-sd!hp-sdd!hplabs!decwrl!purdue!mailrus!ncar!tank!nucsrl!bob
From: bob@eecs.nwu.edu (Bob Hablutzel)
Newsgroups: comp.sys.mac
Subject: Re: Fool Apple, 400k to 800k
Message-ID: <10330050@eecs.nwu.edu>
Date: 9 Oct 88 02:20:22 GMT
References: <880@yabbie.rmit.oz>
Organization: Northwestern U, Evanston IL, USA
Lines: 24

> Im trying to recover data from an 800k disk mistakanly initialised to 400k
> (old 512 machine with the great line Do you want to initialise ? (or eject))
> So Im hoping that data is still on the other side, but symantec tools wont
> scan that side because it thinks it's a 400k.

We ran across this problem A LOT here. (We're a university with a large 
number of Macintosh labs. Around finals week, we'd get at least 2-3 cases
of this happening _a day_). We finally did the following: (if I remember
right, this has been a while :-)) (1) Initialize a blank 800K diskette.
(2) Copy the first 10 sectors or so with FEdit from the blank diskette to
to the improperly initialized diskette. This puts a HFS directory on the
diskette. (3) Attempt to recover files from the diskette as normal.

I think, in hindsight, that if we just found the signature bytes for the
volume, and changed them to the HFS signature bytes (BD, for Big Disk), 
life may have been simpler. The diskette volume map would still be 
completely trashed, but it may have been one step shorter.

Good luck! Believe me, I know exactly what you are going through. Remember:
Always work with a backup of the trashed diskette.

Bob Hablutzel		BOB@NUACC.ACNS.NWU.EDU
Disclaimer:	I finally trained students to do this, and so I could be a 
		little off...