s851736@yabbie.rmit.oz (Robert Krohn) (10/06/88)
Is it possible to fool the mac in thinking a 400k disk is an 800k one ? 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. Any other suggestions wellcomed ! Thanks in advance, Rob. ============================================================================= = = = Robert Krohn RMIT Comm & Elec Eng, Melbourne, Australia. = = = = ACSnet: s851736@yabbie UUCP: ...!uunet!munnari!yabbie.rmit.oz!s851736 = = CSNET: s851736@yabbie.rmit.oz ARPA: s851736@yabbie.rmit.oz@uunet.uu.net = = BITNET: s851736@yabbie.rmit.oz@CSNET-RELAY = = = = 'My God, it's Full of Stars' = = = =============================================================================
jlc@goanna.oz (Jacob L. Cybulski) (10/06/88)
In article <880@yabbie.rmit.oz>, s851736@yabbie.rmit.oz (Robert Krohn) writes: > Is it possible to fool the mac in thinking a 400k disk is an 800k one ? > > 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. I think that the sequence of 800K disk tracks alternate between sides to reduce the head movements during I/O. This means that when you formatted your disk as 400K you've lost every second track of your disk, you know the implications of that... the disk map points in all directions and each of your files has been shattered to zillions of pieces skattered all over the disk of which every second track has been wiped out. Hmmm... it is a sad story. Jacob
bob@eecs.nwu.edu (Bob Hablutzel) (10/09/88)
> 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...