English Amiga Board


Go Back   English Amiga Board > Main > Nostalgia & memories

 
 
Thread Tools
Old 20 January 2017, 06:58   #201
ruinashiro
Registered User

 
Join Date: Jan 2017
Location: Tokyo, Japan
Posts: 20
Quote:
Originally Posted by dlfrsilver View Post
Parasol stars use a mini virtual machine, just check Codetapper's website. Like Jurassic Park, it had tons of copylock disk accesses added to the logical protection added to the code.
I couldn't find any info on Parasol stars using a virtual machine. Do you have a link?
ruinashiro is offline  
Old 20 January 2017, 17:01   #202
deicidal
Registered Insane

deicidal's Avatar
 
Join Date: Feb 2010
Location: Ununited Kingdom
Posts: 787
Quote:
Originally Posted by ruinashiro View Post
I couldn't find any info on Parasol stars using a virtual machine. Do you have a link?
Possibly this http://codetapper.com/amiga/interviews/mick-west/
deicidal is offline  
Old 22 January 2017, 19:26   #203
StingRay
move.l #$c0ff33,throat

StingRay's Avatar
 
Join Date: Dec 2005
Location: Berlin/Joymoney
Posts: 6,103
Quote:
Originally Posted by ruinashiro View Post
I couldn't find any info on Parasol stars using a virtual machine. Do you have a link?
That's because it doesn't! It uses heavily encrypted code but it's nothing that can be called "virtual machine".
StingRay is offline  
Old 22 January 2017, 21:47   #204
dlfrsilver
CaptainM68K-SPS France
dlfrsilver's Avatar
 
Join Date: Dec 2004
Location: Melun nearby Paris/France
Age: 41
Posts: 7,787
Send a message via MSN to dlfrsilver
Quote:
Originally Posted by StingRay View Post
That's because it doesn't! It uses heavily encrypted code but it's nothing that can be called "virtual machine".
Check the source code in the page on codetapper's page. Mick has indeed made a small virtual machine. A very clever idea

That's the OBBLE.S file.

Here are the registers of this small virtual machine :

ob_r0 rs.l 1
ob_r1 rs.l 1
ob_r2 rs.l 1
ob_r3 rs.l 1
ob_r4 rs.l 1
ob_r5 rs.l 1
ob_r6 rs.l 1
ob_r7 rs.l 1
ob_r8 rs.l 1
ob_r9 rs.l 1
ob_r10 rs.l 1
ob_r11 rs.l 1
ob_r12 rs.l 1
ob_r13 rs.l 1
ob_r14 rs.l 1
ob_sp rs.l 1
ob_pc rs.l 1
ob_stack rs.l 16
ob_len rs.b 0

You have register r0 to r14, stack pointer, Pile counter, stack, and length.
dlfrsilver is offline  
Old 26 January 2017, 12:53   #205
Phantasm
Not a Rebel anymore
 
Join Date: Apr 2005
Location: UK
Age: 45
Posts: 193
It definitely does use a virtual machine I documented a little of its functionality (enough to bypass it) in the flashtro tutorial i made although i called it a scripted interpreter

http://www.flashtro.com/index.php?e=...ection&id=4223
Phantasm is offline  
Old 26 January 2017, 19:38   #206
dlfrsilver
CaptainM68K-SPS France
dlfrsilver's Avatar
 
Join Date: Dec 2004
Location: Melun nearby Paris/France
Age: 41
Posts: 7,787
Send a message via MSN to dlfrsilver
Quote:
Originally Posted by Phantasm View Post
It definitely does use a virtual machine I documented a little of its functionality (enough to bypass it) in the flashtro tutorial i made although i called it a scripted interpreter

http://www.flashtro.com/index.php?e=...ection&id=4223
Thanks Phantasm
dlfrsilver is offline  
Old 10 August 2018, 22:03   #207
jotd
Cat freak
jotd's Avatar
 
Join Date: Dec 2004
Location: FRANCE
Age: 47
Posts: 2,560
BTW @Codetapper I still have a lot of hair. But Cruise For a Corpse was not that easy, yes. The crack I had managed to create (using data replay techniques that I successfully used in Sierra games & Lucasfilm but if badly done could corrupt the rest of the game, right) with OSEmu didn't work anymore when I migrated to Kickemu.

After a while, I found a working crack that I adapted for whdload. Easier like this
jotd is offline  
Old 11 August 2018, 22:13   #208
NorthWay
Registered User
 
Join Date: May 2013
Location: Grimstad / Norway
Posts: 480
Quote:
Originally Posted by IFW View Post
Turrican 2 holds the theoretical maximum data that the Amiga controller can read.
Great old thread, so let me do a little necromancing:
(0 - Bubble Bobble was nothing but a compare instruction that you could remove and so skip the whole protection check.)
1 - everyone keeps saying standard MFM data. Did any game use non-standard MFM or not MFM?
2 - I'm pretty sure I read in one of the old Amiga mags about some devs who claimed they had developed their own format that could fit 1.3M on a disk. Did that ever happen?
3 - Are there alternative bit encodings that obey the MFM rules but achieve better than 50% data density?
NorthWay is offline  
Old 12 August 2018, 22:41   #209
Galahad/FLT
Going nowhere

Galahad/FLT's Avatar
 
Join Date: Oct 2001
Location: United Kingdom
Age: 45
Posts: 6,994
Quote:
Originally Posted by NorthWay View Post
Great old thread, so let me do a little necromancing:
(0 - Bubble Bobble was nothing but a compare instruction that you could remove and so skip the whole protection check.)
1 - everyone keeps saying standard MFM data. Did any game use non-standard MFM or not MFM?
2 - I'm pretty sure I read in one of the old Amiga mags about some devs who claimed they had developed their own format that could fit 1.3M on a disk. Did that ever happen?
3 - Are there alternative bit encodings that obey the MFM rules but achieve better than 50% data density?
Well technically, MFM data applies to a standard AmigaDOS formatted disk, but the term "MFM protection" was used to describe in cracking circles as a copy protected disk where every track would show as an error on a copy program, and each track would need to be decoded, or the disk would need to be dumb read or cracked to standard AmigaDOS files.

Pretty sure the Psygnosis format as used on SOTB 1 and 2, Awesome and a few others was pretty close to 1.3m per disk, hence why Psygnosis were so keen on it.

It was possible to exceed the data capacity of Turrican 2, but Turrican 2 was what all drives could cope with, going much larger didn't guarantee that it would work on all drives which was obviously not encouraged.
Galahad/FLT is offline  
Old 12 August 2018, 23:46   #210
Rotareneg
Registered User

 
Join Date: Sep 2017
Location: Kansas, USA
Posts: 57
How much data is on the Turrican 2 disc?
Rotareneg is offline  
Old 13 August 2018, 05:28   #211
dlfrsilver
CaptainM68K-SPS France
dlfrsilver's Avatar
 
Join Date: Dec 2004
Location: Melun nearby Paris/France
Age: 41
Posts: 7,787
Send a message via MSN to dlfrsilver
Quote:
Originally Posted by Rotareneg View Post
How much data is on the Turrican 2 disc?
mmhh 1100kb of data.
dlfrsilver is offline  
Old 13 August 2018, 09:39   #212
jotd
Cat freak
jotd's Avatar
 
Join Date: Dec 2004
Location: FRANCE
Age: 47
Posts: 2,560
Beast 2 disks take 1,008,000 bytes on disk once ripped, so big, but not 1.3M. More than the other Psygnosis or 12-sector per track protected MFM (980k)
jotd is offline  
Old 13 August 2018, 11:44   #213
Galahad/FLT
Going nowhere

Galahad/FLT's Avatar
 
Join Date: Oct 2001
Location: United Kingdom
Age: 45
Posts: 6,994
Quote:
Originally Posted by jotd View Post
Beast 2 disks take 1,008,000 bytes on disk once ripped, so big, but not 1.3M. More than the other Psygnosis or 12-sector per track protected MFM (980k)
Nitro beats that. 1,035,036 bytes on disk
Galahad/FLT is offline  
Old 13 August 2018, 12:16   #214
NorthWay
Registered User
 
Join Date: May 2013
Location: Grimstad / Norway
Posts: 480
Quote:
Originally Posted by Galahad/FLT View Post
It was possible to exceed the data capacity of Turrican 2, but Turrican 2 was what all drives could cope with
I tried googling a bit, and what I understood from it is that the limits are no more than one '1' bit in a row, and no more than three '0' bits in a row.
Has anyone tested this with the Amiga controller, and tried exceeding this? I originally thought the limit was "no more than 2 identical bits in a row" as that could make the timing of the controller start drifting. I find it interesting that the specs allow 3 '0's in a row.
Why would 3 '1's in a row be different to 3 '0's in a row?
Is the encoding actually "rising", "no change", "falling" - each being returned as 2 bits? That would explain not having any possible '11' pattern as it would be the same as '00'. In which case it should be possible to do an alternative MFM version where you replace '00' with '11' - unless the controller freaks out or just silently makes it '00'?
NorthWay is offline  
Old 13 August 2018, 12:16   #215
dlfrsilver
CaptainM68K-SPS France
dlfrsilver's Avatar
 
Join Date: Dec 2004
Location: Melun nearby Paris/France
Age: 41
Posts: 7,787
Send a message via MSN to dlfrsilver
Obitus disk 1 is going a bit higher than that
dlfrsilver is offline  
Old 15 August 2018, 15:45   #216
Phantasm
Not a Rebel anymore
 
Join Date: Apr 2005
Location: UK
Age: 45
Posts: 193
when i was messing around with creating custom mfm formatted disks i found that when you pushed the limits it was often the case that you could create stuff that would read back fine on the same drive but then if you try and put the disk into a different drive and read it, you might start to see issues
Phantasm is offline  
Old 17 August 2018, 15:51   #217
jotd
Cat freak
jotd's Avatar
 
Join Date: Dec 2004
Location: FRANCE
Age: 47
Posts: 2,560
It's possible that using GCR has no interest at all because it can be copied easily / re-read using the original game routine...

Well, want to see a counter example of a "good protection"? check "Captain Fizz":

Code:
	SECTION S_0,CODE

	MOVEA.L	#$00060000,A0		;0000: 207c00060000
	JSR	_protec			;0006: 4eb90000eb60
	CMPI.B	#$00,D0			;000c: 0c000000
	BEQ.W	LAB_0001		;0010: 67000006
LAB_0000:
	JMP	LAB_0000(PC)		;0014: 4efafffe  ; oh no, infinite loop. That really crashed the machine for good...
LAB_0001:
       ...
    ; now the "protec" routine (I wonder what that means ....)
_protec:
	MOVEM.L	D1-D7/A1-A6,-(A7)	;eb60: 48e77f7e
	MOVE.L	A0,DUBUFF		;eb64: 23c80000edc0
	JSR	init			;eb6a: 4eb90000eb9a
	JSR	startd			;eb70: 4eb90000ebf0
	JSR	gotot0			;eb76: 4eb90000ec20
	JSR	readtr			;eb7c: 4eb90000ec8c
	JSR	clear			;eb82: 4eb90000ecfa
	JSR	fsig			;eb88: 4eb90000ed4c
	MOVE.B	status,D0		;eb8e: 10390000edcc
	MOVEM.L	(A7)+,D1-D7/A1-A6	;eb94: 4cdf7efe
	RTS				;eb98: 4e75
       ... rest of the routine follows with clear symbols inc. variables
I'll add that I just disassembled the executable with IRA, the symbols were stripped in all sections but the protection section. I guess the protection team didn't know about them (well, even without the symbols it's trivial to crack: average time to crack it: 30 seconds)
jotd is offline  
Old 22 August 2018, 17:39   #218
8bitbubsy
Registered User

8bitbubsy's Avatar
 
Join Date: Sep 2009
Location: Norway
Posts: 1,278
That's amazingly bad protection indeed, unless it has integrity checks deep within the game or something.
8bitbubsy is offline  
Old 09 September 2018, 18:44   #219
StingRay
move.l #$c0ff33,throat

StingRay's Avatar
 
Join Date: Dec 2005
Location: Berlin/Joymoney
Posts: 6,103
Quote:
Originally Posted by jotd View Post
Well, want to see a counter example of a "good protection"? check "Captain Fizz":

Good one, but I have a better one. To "crack" the game Cougar Force all that has to be done is this: open startup-sequence, remove/comment the "loader" entry, save startup-sequence and lo and behold, the game is "cracked". Incredibly useless "protection" but somewhat entertaining.
StingRay is offline  
Old 09 September 2018, 21:36   #220
jotd
Cat freak
jotd's Avatar
 
Join Date: Dec 2004
Location: FRANCE
Age: 47
Posts: 2,560
Stingray that must be a record. I've seen "protect" symbols (Thexder is "protected" like this too), hacked unpackers that you by pass by using the official one, but never the "script protection scheme"
jotd is offline  
 


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Similar Threads
Thread Thread Starter Forum Replies Last Post
Pcmcia tough question marcolau support.Hardware 8 08 November 2009 12:41
This one will be tough. comawhite015 Looking for a game name ? 9 29 June 2006 16:08
games name? tough on jackoland Looking for a game name ? 8 05 May 2006 13:59
WHDLoad crack games compatibility GoKu project.WHDLoad 6 25 September 2005 18:17
heres some tough ones i cant find:( lee uk request.Old Rare Games 3 16 May 2002 23:13

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +2. The time now is 14:38.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.
Page generated in 0.09671 seconds with 15 queries