jimli@milton.acs.washington.edu (Jimmy Li) (04/14/90)
I'd like to know if there is any way to know if a floppy disk has been copied. It doesn't seem to be possible to me. But a friend of mine insists that it could be done. Any ideas? -Jimmy.
cs472309@umbc5.umbc.edu (CMSC 472/03011) (04/14/90)
In article <2885@milton.acs.washington.edu> jimli@milton.acs.washington.edu (Jimmy Li) writes: >I'd like to know if there is any way to know if a floppy disk has been copied. >It doesn't seem to be possible to me. But a friend of mine insists that it >could be done. > >Any ideas? >-Jimmy. If you are copying from one floppy to another and they are both the same type (double density, high density, etc.), the DOS command DISKCOMP x: y: will compare the contents of two floppies, where you would substitute the actual drive letters for x and y. You could compare the original floppy to the copy and verify the copy that way. Mike Reese -- University of Maryland Baltimore County Please send mail to: ARPANET - MZR@DETRICK-HSC.ARMY.MIL (26.6.0.54) REESEM@ILCN-DETRICK.ARPA (26.5.0.54)
srg@cunixd.cc.columbia.edu (Steven R Gerber) (04/15/90)
In article <3133@umbc3.UMBC.EDU> cs472309@umbc5.umbc.edu.UUCP (CMSC 472/03011) writes: >In article <2885@milton.acs.washington.edu> jimli@milton.acs.washington.edu (Jimmy Li) writes: >>I'd like to know if there is any way to know if a floppy disk has been copied. >>It doesn't seem to be possible to me. But a friend of mine insists that it >>could be done. >> >>Any ideas? >>-Jimmy. > >If you are copying from one floppy to another and they are both the >same type (double density, high density, etc.), the DOS command >DISKCOMP x: y: will compare the contents of two floppies, where you >would substitute the actual drive letters for x and y. You could >compare the original floppy to the copy and verify the copy that way. > > Mike Reese -- University of Maryland Baltimore County > > Please send mail to: ARPANET - MZR@DETRICK-HSC.ARMY.MIL (26.6.0.54) > REESEM@ILCN-DETRICK.ARPA (26.5.0.54) Mike, I don't think that's what Jimmy is talking about. I think he means "Taking any given (single) diskette, can you determine whether or not a copy has been made of it?". My answer: NO. **************************************************************** * Steven R. Gerber - PAL (Programmer At Large) * srg@cunixd.cc.columbia.edu * Tel: 212-794-8721 * UUCP: ...rutgers!columbia!cunixd!srg * FAX: 212-794-8722 ****************************************************************
nraoaoc@nmtsun.nmt.edu (Daniel Briggs) (04/15/90)
In article <2885@milton.acs.washington.edu> jimli@milton.acs.washington.edu (Jimmy Li) writes: >I'd like to know if there is any way to know if a floppy disk has been copied. >It doesn't seem to be possible to me. But a friend of mine insists that it >could be done. > >Any ideas? >-Jimmy. I think I may have heard some folk tales about what your friend is driving at. I have *no* idea if this is true, or even possible. I merely toss this out as an example of this kind of reasoning. What you would need would be some sort of data on the disk that would be destroyed by the process of reading. (Say a bit that is on the very marginal edge of validity, or a pattern of them designed to take advantage of some physical property of the read/write head.) This data would be put somewhere on the disk where normal DOS calls wouldn't get at it, (but possibly where a disk-to-disk copy would?) Does anyone know if there are any intertrack areas that are not normally accessed by normal sector reads, but would get scanned by a disk copy? Anyway, what's worse still is that you also need a program that is capable of driving the disk hardware close enough the flag data to see if it's still OK, but not close enough to zap it. Sounds very hardware dependant to say the least, a nightmare of calibration probably, and impossible possibly. I have no doubt that this kind of stunt might be doable in Maxell's recording media development lab, but it sounds awful damned iffy with off the shelf PC hardware. Lest you think that I am completely off base, I point out that there is a copy protection scheme that is *sort of* based on the same kind of techniques. (That is, using non-linear effects in the media.) That's the one where the original disk drives write bits that are smack in the middle of the indeterminate region between 1-and-0. A normal drive will read this back sometimes as 1 and sometimes as 0. The software, of course, checks for this property. When this disk is copied, the destination drive writes a 1 or a 0, but not both. I always thought that this was kind of a neat trick. ----- This is a shared guest account, please send replies to dbriggs@nrao.edu (Internet) Dan Briggs / NRAO / P.O. Box O / Socorro, NM / 87801 (U.S. Snail)
jca@pnet01.cts.com (John C. Archambeau) (04/15/90)
jimli@milton.acs.washington.edu (Jimmy Li) writes: >I'd like to know if there is any way to know if a floppy disk has been copied. >It doesn't seem to be possible to me. But a friend of mine insists that it >could be done. You can verify the copy with diskcomp which just does a byte by byte, sector by sector compare of two disks and reports any differences. Obviously if they compare ok then the disk is a duplicate. If you mean if there's a flag on the disk that indicates that it has been copied, that I don't know. // JCA /* **--------------------------------------------------------------------------* ** Flames : /dev/null | My opinions are exactly that, ** ARPANET : crash!pnet01!jca@nosc.mil | mine. Bill Gates couldn't buy ** INTERNET: jca@pnet01.cts.com | it, but he could rent it. :) ** UUCP : {nosc ucsd hplabs!hd-sdd}!crash!pnet01!jca **--------------------------------------------------------------------------* */
cs472309@umbc5.umbc.edu (CMSC 472/03011) (04/15/90)
In article <1990Apr14.174605.18601@cunixf.cc.columbia.edu> srg@cunixd.cc.columbia.edu (Steven R Gerber) writes: >>>I'd like to know if there is any way to know if a floppy disk has been copied.... >>If you are copying from one floppy to another and they are both the... >> >> Mike Reese -- University of Maryland Baltimore County > >Mike, I don't think that's what Jimmy is talking about.... See what happens when I try to answer a question at 2 a.m. when I'm half asleep? Now that I understand the question, I don't know of any way to detect if a disk has been copied or not. Can anyone out there correct/clarify this?? Mike Reese -- University of Maryland Baltimore County Please send mail to: ARPANET - MZR@DETRICK-HSC.ARMY.MIL (26.6.0.54) REESEM@ILCN-DETRICK.ARPA (26.5.0.54)