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⬅️ Previous capture (2023-01-29)
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-------------Robotron 2084-------------
A 4am crack 2015-03-06
---------------------------------------
Name: Robotron 2084
Genre: arcade
Year: 1983
Publisher: Atari, Inc.
Media: single-sided 5.25-inch floppy
OS: DOS 3.3
Other versions:
- The Mask of Death crack
- Cygnus crack
- various uncredited cracks
- Asimov also has an uncracked .nib
Identical cracks: Stargate (4am crack
no. 243)
~
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 addres and data epilogue
bytes ("AA DE EB" for each)
Disk Fixer
["O" -> "Input/Output Control"]
set Address Epilogue to "AA DE EB"
set Data Epilogue to "AA DE EB"
all tracks readable
T00 -> looks like a DOS 3.3 RWTS
T11 -> DOS 3.3 disk catalog
T01,S09 -> startup program is RUNNER
Why didn't COPYA work?
modified epilogue bytes (every track)
Why didn't Locksmith FDB work?
modified epilogue bytes (every track)
Next steps:
1. capture RWTS with AUTOTRACE
2. convert disk to standard format
with Advanced Demuffin
3. there is no step 3 (I hope)
~
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,$0F BY1.0 S6,D1->S6,D2
--^--
]PR#5
]CATALOG,S6,D2
C1983 DSR^C#254
394 FREE
A 002 RUNNER
B 100 ROBOTRON
]RUN RUNNER
ERROR #11 SYNTAX
BREAK IN 10
]LIST
]LIST
10 HOME : CLEAR : PRINT CHR$ (
4);"BNROBOTRON"
Ah, OK. The DOS on the original disk
redefines the DOS commands. It uses
"BN" instead of "BRUN".
]BRUN ROBOTRON
...works...
There we go.
[S6,D1=demuffin'd copy]
]PR#6
...grinds...
My copy can't read itself yet. I have a
tool to fix that.
~
Chapter 2
In Which We Remove All Traces Of Copy
Protection Using An Automated Tool That
I Wrote For Just Such An Occasion
And Then It Crashes Anyway
[S6,D1=demuffin'd copy]
[S5,D1=my work disk]
]PR#5
]BRUN PDP
T00,S03,$91 change AA to DE
T00,S03,$9B change DE to AA
T00,S03,$35 change AA to DE
T00,S03,$3F change DE to AA
T00,S06,$AE change AA to DE
T00,S06,$B3 change DE to AA
T00,S02,$9E change AA to DE
T00,S02,$A3 change DE to AA
]PR#6
...crashes at $9D86...
Wait, what?
After minutes of furious investigation,
I hit upon the source of the problem:
the disk volume number. The original
disk uses disk volume 100, but the
process of converting it with Advanced
Demuffin gives me a (non-working) copy
with disk volume 254. (This is encoded
in every sector's address field.)
Why is this a problem? Well, besides
appearing in every sector's address
field, the volume number is stored in
four different places when a disk is
initialized:
1. $B7EB (T00,S01,$EB), in the RWTS
parameter table used by boot1 to
load DOS from tracks 0-2 ["Beneath
Apple DOS", p. 8-35]
2. $B7F6 (T00,S01,$F6), also in the
RWTS parameter table, as the "last
found" disk volume
3. $AA66 (T01,S09,$66), in the parsed
keyword table used by DOS to load
the startup program (and every other
file loaded after that) [ibid.,
p. 8-21]
4. $B3C1 (T11,S00,$06), in the VTOC
header [ibid., p. 8-32]
My (non-working) copy has a $64 in each
of those locations. Since this doesn't
match the actual disk volume number in
the address fields, every sector read
fails and DOS never loads. (Why did it
work when I booted from my work disk?
Because that loaded DOS from a separate
disk that was already disk volume 254,
thus matching up with the actual disk
volume number in my non-working copy's
address fields.)
Using my trusty Disk Fixer sector
editor, I changed each of the
aforementioned locations to $FE.
T00,S01,$EB change 64 to FE
T00,S01,$F6 change 64 to FE
T01,S09,$66 change 64 to FE
T11,S06,$06 change 64 to FE
Success! My copy finally boots and runs
on its own. There doesn't appear to be
any further copy protection.
(Note to self: add this to a future
version of Post-Demuffin Patcher.)
Quod erat liberandum.
---------------------------------------
A 4am crack No. 244
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