-------------Terrapin Logo-------------
A 4am crack                  2015-11-06
---------------------------------------

Name: Terrapin Logo
Version: 1.0
Genre: educational
Year: 1981
Authors: L. Klotz, P. Sobalvarro, S.
  Hain, H. Abelson
Publisher: Terrapin, Inc.
Media: two single-sided 5.25-inch discs
OS: DOS 3.3
Previous cracks: Asimov has an
  uncredited crack
Identical cracks:
  #420 Fact or Opinion
  #419 Who What When Where
  #351 Home Row

Disk 1 is labeled "program"; disk 2 is
labeled "utilities". I'll start with
disk 1.

                   ~

               Chapter 0
 In Which Various Automated Tools Fail
          In Interesting Ways


COPYA
  immediate disk read error

Locksmith Fast Disk Backup
  unable to read any track

EDD 4 bit copy (no sync, no count)
  works

Copy ][+ nibble editor
  modified address and data epilogues
  ("DA AA EB" instead of "DE AA EB")

Disk Fixer
  ["O" -> "Input/Output Control"]
    set Address Epilogue to "DA AA EB"
    set Data Epilogue to "DA AA EB"
  all tracks readable
  T00 -> looks like a DOS 3.3 RWTS
  T11 -> DOS 3.3 disk catalog
  T01,S09 -> startup program is
    "STARTLOGO"

Why didn't COPYA work?
  modified epilogue bytes (every track)

Why didn't Locksmith FDB work?
  modified epilogue bytes (every track)

EDD worked. What does that tell us?
  no half or quarter tracks
  almost certainly no nibble check
  (just structural changes to epilogue)

Next steps:

  1. capture RWTS with AUTOTRACE
  2. convert disk to standard format
     with Advanced Demuffin
  3. patch RWTS to read standard format

                   ~

               Chapter 1
In Which We Attempt To Use The Original
    Disk As A Weapon Against Itself


[S6,D1=original disk]
[S6,D2=blank disk]
[S5,D1=my work disk]

]PR#5
CAPTURING BOOT0
...reboots slot 6...
...reboots slot 5...
SAVING BOOT0
CAPTURING BOOT1
...reboots slot 6...
...reboots slot 5...
SAVING BOOT1
SAVING RWTS

]BRUN ADVANCED DEMUFFIN 1.5

["5" to switch to slot 5]

["R" to load a new RWTS module]
  --> At $B8, load "RWTS" from drive 1

["6" to switch to slot 6]

["C" to convert disk]

                 --v--

ADVANCED DEMUFFIN 1.5    (C) 1983, 2014
ORIGINAL BY THE STACK    UPDATES BY 4AM
=======PRESS ANY KEY TO CONTINUE=======
TRK:...................................
+.5:
    0123456789ABCDEF0123456789ABCDEF012
SC0:...................................
SC1:...................................
SC2:...................................
SC3:...................................
SC4:...................................
SC5:...................................
SC6:...................................
SC7:...................................
SC8:...................................
SC9:...................................
SCA:...................................
SCB:...................................
SCC:...................................
SCD:...................................
SCE:...................................
SCF:...................................
=======================================
16SC $00,$00-$22,$0F BY1.0 S6,D1->S6,D2

                 --^--

]PR#5
...
]CATALOG,S6,D2

 B 002 STARTLOGO
 B 128 LOGO

]BRUN STARTLOGO
...crashes...

[S5,D1=DOS 3.3 master disk]

]PR#5
]BRUN STARTLOGO,S6,D2
...program loads and runs...

So it doesn't like Diversi-DOS 64K (the
DOS on my work disk). It's probably
accessing DOS functions directly or
assuming the RWTS parameter table is at
specific address, instead of using the
vectors on page 3. But it works when I
boot an unmodified DOS 3.3 first, so it
isn't checking for its original DOS at
runtime.

[S6,D1=demuffin'd copy]

]PR#6
...grinds then crashes...

The demuffin'd disk can't read itself.
This is not unusual.

                   ~

               Chapter 2
 In Which We Remove All Traces Of Copy
Protection Using An Automated Tool That
   I Wrote For Just Such An Occasion


[S6,D1=demuffin'd copy]
[S5,D1=my work disk]

]PR#5
]BRUN PDP

T00,S03,$91 change DA to DE
T00,S03,$35 change DA to DE
T00,S02,$9E change DA to DE

Disk 2 is unprotected.

Quod erat liberandum.

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A 4am crack                     No. 488
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