---------Just Around The Block---------
A 4am crack                  2021-04-18
---------------------------------------

Name: Just Around The Block
Genre: educational
Year: 1987
Credits: Rob Shaver, Peter Andrews
Publisher: D.C. Heath and Company
Platform: Apple //e or later (128K)
Media: 5.25-inch disk
Sides: 2
OS: ProDOS 1.2
Previous cracks: none

This disk was automatically cracked by
Passport. Here is the transcript for
disk 1:

                 --v--

Reading from S6,D1
T00,S00 Found ProDOS bootloader
T00,S0B Volume name is EXPLORE
Using built-in RWTS
Writing to RAM disk
Writing to S6,D2

The disk was copied successfully, but
Passport did not apply any patches.

Possible reasons:
- The source disk is not copy protected.
- The target disk works without patches.
- The disk uses an unknown protection,
  and Passport can not help any further.

Press any key

                 --^--

Wait, what?

Looking more closely at the original
disk, it is absolutely protected. COPYA
(my go-to program for determining if a
disk has any modified structure at all,
because it does everything absolutely
"by the book") immediately fails to
read the original disk.

The Copy II Plus nibble editor confirms
that the disk uses slightly modified
RWTS parameters: a $DE $DE $EB address
epilogue instead of the usual
$DE $AA $EB.

                 --v--

   COPY ][ PLUS BIT COPY PROGRAM 8.4
(C) 1982-9 CENTRAL POINT SOFTWARE, INC.
----------------------------------------

TRACK: 00  START: 1AE1  LENGTH: 1859

1AC0: FF FF FF FF FF FF FF FF   VIEW
1AC8: FF FF FF FF FF FF FF FF
1AD0: FF FF FF FF FF FF FF FF
1AD8: FF FF FF FF FF FF FF FF
1AE0: FF D5 AA 96 AA AB AA AA  <-1AE1
         ^^^^^^^^
         prologue

1AE8: AA AA AA AB DE DE EB FF
                  ^^^^^^^^
                  epilogue

1AF0: FF FF FF FF FF D5 AA AD
1AF8: AC B6 ED F2 FF 9E B7 FB
1B00: D9 F9 FD F6 F9 DA EF EE

                 --^--

This is, in one sense, very clever.
ProDOS only verifies the first nibble
after the address prologue, so this
disk could be mastered -- protected --
without changing a single byte of the
on-disk operating system!

And Passport was correct: "the target
disk works without patches." Not in a
way I've seen before, but it works
nonetheless.

Quod erat liberandum.

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A 4am crack                    No. 2611
------------------EOF------------------