X-Authentication-Warning:	delorie.com: mail set sender to djgpp-bounces using -f
From:	Jack Klein <jackklein AT spamcop DOT net>
Newsgroups:	comp.os.msdos.programmer,comp.os.msdos.djgpp
Subject:	Re: Creating a copy protected floppy
Date:	Thu, 14 Jul 2005 23:16:55 -0500
Organization:	Posted via Supernews, http://www.supernews.com
Message-ID:	<crded1pfuh52svet997hfodlju25a55i5u@4ax.com>
References:	<1121199731 DOT 361001 DOT 326030 AT g43g2000cwa DOT googlegroups DOT com> <qtu8d1h1ot3deg6sfpo8a3fuk8bprasl7s AT 4ax DOT com> <Pine DOT GSO DOT 3 DOT 95 DOT iB1 DOT 0 DOT 1050713053319 DOT 19585A-100000 AT halifax DOT chebucto DOT ns DOT ca> <1121251420 DOT 008623 DOT 117040 AT f14g2000cwb DOT googlegroups DOT com> <yH9Be.4398$Hx2 DOT 1649 AT reader1 DOT news DOT jippii DOT net> <1121304613 DOT 063822 DOT 249190 AT g14g2000cwa DOT googlegroups DOT com> <3TmBe.4559$Gy5 DOT 2289 AT reader1 DOT news DOT jippii DOT net>
X-Newsreader:	Forte Agent 2.0/32.652
MIME-Version:	1.0
X-Complaints-To:	abuse AT supernews DOT com
Lines:	56
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp
Reply-To:	djgpp AT delorie DOT com

On Thu, 14 Jul 2005 08:32:20 +0300, Ari Lukumies
<nospam DOT ari DOT lukumies AT gmail DOT com DOT invalid> wrote in
comp.os.msdos.programmer:

> RetroMIDI wrote:
> > It is possible to write EXTRA sectors on a particular track so that the
> > sector numbers are within the data sections of lower numbered sectors.
> 
> You do not need to mess the sectors up this way, however, if you don't 
> want to. An easy way to "hide" some of your data (although not so hard 
> to get around with, either) is to format a disk with more than the 
> standard number of sectors on tracks (and with more tracks), while 
> retaining the standard DPB (disk parameter block), so a "normal" copy 
> program only copies the standard sectors and tracks, ignoring the 
> nonstandard ones. For those interested, see Ralf Brown's interrupt list,
> 
> http://www.ctyme.com/intr/cat.htm
> 
> especially the DPB:
> 
> http://www.ctyme.com/intr/rb-2445.htm
> 
> -atl-

There were some commercial companies that got themselves into a lot of
trouble years ago doing that.

I can't remember for sure if it was the original IBM PC, or the PC Jr,
but one of them had a floppy disk drive with enough stroke on the head
to be able to read and write 41 tracks instead of the normal 40 on a
floppy.

Some companies put their own custom, non-standard format and some data
on that extra innermost track.  If an (unknowing) user used the
standard diskcopy to try and make a program disk for a friend, only
the normal 40 tracks were copied.

When the program started, it used either BIOS or direct hardware
access to the disk controller to read the extra track.  If the disk
was a copy, the data wasn't there and the program would not run.

Then IBM changed suppliers for the disk drive in that particular
computer, and the new disk drive did not have the extra stroke to read
the 41st track...

Wasn't is Lotus who used to use a laser to burn a hole at a particular
spot on the program disk?

-- 
Jack Klein
Home: http://JK-Technology.Com
FAQs for
comp.lang.c http://www.eskimo.com/~scs/C-faq/top.html
comp.lang.c++ http://www.parashift.com/c++-faq-lite/
alt.comp.lang.learn.c-c++
http://www.contrib.andrew.cmu.edu/~ajo/docs/FAQ-acllc.html

- Raw text -