---------Grasshopper Dissection--------
A 4am crack                  2017-01-14
---------------------------------------

Name: Grasshopper Dissection
Genre: educational
Year: 1984 / 1990 reissue
Credits: Larry C. Newby
Publisher: Cross Educational Software
Platform: Apple ][+ or later
Media: double-sided 5.25-inch floppy
OS: Protected.DOS

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

                 --v--

READING FROM S6,D1
T00,S00 FOUND DOS 3.3 BOOTLOADER
T00,S01 FOUND ENCRYPTED RWTS, KEY=$DB
USING DISK'S OWN RWTS
WRITING TO S5,D2
T01,S02 ERASING SERIAL NUMBER 000013
T01,S02,$B0: B5 -> AD
T01,S02,$B7: D5 -> 9B
T00,S0B ERASING SERIAL NUMBER 000013
T00 DECRYPTING RWTS BEFORE WRITING
T00,S01,$07: 99 -> 2C
T00,S01,$93: 4C00B8 -> ACE5B7
T00,S05,$15: A52F -> A900
CRACK COMPLETE.

                 --^--

And side B:

                 --v--

READING FROM S6,D1
T00,S00 FOUND DOS 3.3 BOOTLOADER
T00,S01 FOUND ENCRYPTED RWTS, KEY=$1F
USING DISK'S OWN RWTS
WRITING TO S5,D2
T01,S02 ERASING SERIAL NUMBER 000008
T01,S02,$B0: B5 -> AD
T01,S02,$B7: D5 -> 9B
T00,S0B ERASING SERIAL NUMBER 000008
T00 DECRYPTING RWTS BEFORE WRITING
T00,S01,$07: 99 -> 2C
T00,S01,$93: 4C00B8 -> ACE5B7
T00,S05,$15: A52F -> A900
CRACK COMPLETE.

                 --^--

More information and source code is
available at
https://archive.org/details/Passport4am

Quod erat liberandum.

                   ~

               Epilogue
           Behind The Crack


Side A was clean. I was able to crack
it with Passport on the first try, and
I got a clean .edd image which verifies
in an emulator.

Side B was quite damaged; I was unable
to get a clean read in one pass. I
added a compile-time flag to Passport
to re-read bad sectors forever. With
that in place, I was eventually able to
read side B all the way through once,
then most of the way through again. The
two images did not match, and neither
image worked fully.

Luckily, the program is a single BASIC
BASIC program that prints text (stored
as strings in the program) and displays
images stored in a compressed format as
separate files on disk). The image
format is quite unforgiving, so any
errors in those files showed obvious
visual glitches.

I ended up comparing several sectors
from each image and manually stitching
together a working image. I exercised
the entire BASIC program and all the
compressed images. Everything works.

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A 4am crack                     No. 961
------------------EOF------------------