Re: software question

[dalloff@freenet.columbus.oh.us (Dave Althoff)]

mynes2@marshall.edu wrote:
: What is locksmith?  I have several versions and want to know what it
: is.

It's a bit-copier for Apple ][ 5.25" disks.

You see, Apple ][ disks are completely soft-formatted...that is, the
timing hole in the disk is ignored by the hardware, and software does
*everything* to find data on the disk.  This simplifies the hardware, and
explains why Apple ]['s can only get 143k onto one side of a 5.25" disk
instead of 180k as on a PC disk (there are other reasons as well, but that
doesn't have much to do with the current question.)

As you are probably aware, Apple disks are logicallly divided up into
30-some tracks of 16 sectors each, with 256 bytes per sector.  Even ProDOS
disks are divided up in this fashion; each ProDOS block is in fact two
disk sectors.  I believe this is to make the ROM code for booting a disk
continue to function, as it expects 16-sector disks.  If it weren't for
that, there would be nothing to stop ProDOS from using 8-sector tracks
with 512 bytes/sector.  Again, I am straying from the topic.

Well, the fact that Apple's disks are soft-formatted got some ingenious
programmers thinking.  They reasoned that so long as they leave Track $00
alone enough that it will actually begin to boot, and they put enough boot
code on Track $00, they can do whatever they want with the remainder of
the disk.  They can change the timing, they can change the sector size,
they can change the number of sectors...heck, they can even change the
physical location of the tracks.  The purpose of all this, of course, is
to prevent people from making copies of the disk.  Copy programs generally
assume they know what the disk looks like, and where the data is supposed
to be, and how it is supposed to be organized.  By messing up some of that
data, a disk becomes impossible to copy using the more primitive methods.

Along comes Locksmith.  Locksmith is designed to break copy protection
schemes by attempting to make an exact copy of the original disk, without
making any assumptions about what the disk looks like.  Of course, this
meant an arms race between the designers of protection schemes and the
authors of Locksmith, a race which came to an inglorious end as several
things happened--
a)  The DuoDisk began munging copy-protected disks
b)  More and more publishers gave up on copy protection
c)  Apple introduced ProDOS and encouraged vendors to use it.  ProDOS does not
    lend itself very well to software copy protection schemes, leading instead
    to those damned code-wheels...
d)  Well, you know what ultimately happened to Apple ][ publishing... 8-(

Does that help?

--Dave Althoff, ][.
-- 
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