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Old 20 January 2017, 06:58   #201
ruinashiro
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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?
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Old 20 January 2017, 17:01   #202
deicidal
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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/
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Old 22 January 2017, 19:26   #203
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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".
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Old 22 January 2017, 21:47   #204
dlfrsilver
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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.
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Old 26 January 2017, 12:53   #205
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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
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Old 26 January 2017, 19:38   #206
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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
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Old 10 August 2018, 22:03   #207
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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
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Old 11 August 2018, 22:13   #208
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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?
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Old 12 August 2018, 22:41   #209
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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.
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Old 12 August 2018, 23:46   #210
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How much data is on the Turrican 2 disc?
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Old Yesterday, 05:28   #211
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Originally Posted by Rotareneg View Post
How much data is on the Turrican 2 disc?
mmhh 1100kb of data.
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Old Yesterday, 09:39   #212
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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)
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Old Yesterday, 11:44   #213
Galahad/FLT
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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
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Old Yesterday, 12:16   #214
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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'?
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Old Yesterday, 12:16   #215
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Obitus disk 1 is going a bit higher than that
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