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2600 Rom Comparisions and Dumps


Omegamatrix

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Berzerk (Unknown) (PAL) [a] is actually an NTSC hack. The only differences between it and the verified good dump of the NTSC version are timer values adjusted in the wrong spots, and an erased logo. The entire program, data, and color palette is otherwise the same as NTSC.

 

BTW Berzerk (Unknown) (PAL) is a PAL hack that's missing the logo (and also the head of reserve lives!).

 

Theory:

Perhaps a pirate version (Unknown [a]) was produced for PAL televisions using the NTSC version as it's base (hence the 99% identical code with NTSC)? This version could have been replaced by (Unknown) once Atari released their own PAL version to hack out the logo (explaining the otherwise 100% identical code between those). Hmm...

 

Here's a -very- rough disassembly that combines all the versions so you can see where the program itself differs...

The Berzerk (Unknown) PAL I have matched before on my 208 in multicart as game #44 Down Town. I found many games that were of NTSC origin, converted to PAL only by changing the literals loaded into the timer for Vblank and Overscan. In other words they didn't do too much, but some of these games were previously unavailable in PAL format. I guess a pirate is better then nothing.

 

 

I didn't look at Berzerk as it was already in Rom's rom set. I only looked at the new images, and found several of them differed only in the timers.

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Here is a partial Crackpots disassembly for you Nukey. Besides the differences in graphics there are some differences at $FFFF, and the "original" CCE version has a compare instruction at $F511 zeroed (instead of compare with #$14). This zeroing seems to stop the copyright\logo from scrolling.

 

 

I would think that the CCE [a] version is actually the original, and the CCE original the actual [a]. This is because the logo is fatter, and it looks funny with the color bars scrolling with nothing behind them.

 

 

Crackpots_multi_.zip

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Yikes! Now things are getting really involved :)

 

Cookie Monster Munch just has differing hotspot values between the 2 versions. Take your pick of them. The "original" uses values $FF in the alternate hotspot address in either bank. All zeros in the [a] version. According to GoodTools, the "original" with the $FF's is the verified good dump.

 

 

Congo Bongo (1983) (Sega - Beck-Tech) (006-01) and [a] have differing hotspot values. No biggie...as we are basically ignoring those. In the "original" game, the first bank's vectors point directly at the init routine instead of going through it's generic bankswitch routine to get there. Neither one is a bad dump. They both arrive safely through different means.

 

 

Commando Raid only features 2 values that change between versions...and they are both timer values. These instructions exist at $F0BE and $F4AC.

The original uses $40 and $23 which produces 292 scanlines, [a] uses $48 and $2D which produces 308 (closer to the PAL standard of 312). Neither one looks to be a bad dump.

 

 

All the rest need a bit more legwork...

Edited by Nukey Shay
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BTW all the rest I'd consider to be valid [a]lternates. I forgot what I was supposed to be doing :lol:

Bugs Bunny, Cat Trax, Chopper Command, Commando, Commie Mutants, Cosmic Ark (CCE), and Cosmic Ark (Reaction) each contain so many changes that they are undoubtedly -not- dump glitches.

 

 

Cosmic Ark (CCE), for example, only features an -slightly- altered logo. The bitmaps move down 1 byte and to the right 1 pixel in [a]. Really odd that this slight change would warrent a different version...but CCE were always queer ducks ;)

 

 

Disassembling Cat Trax now. Only a handful of altered bytes (the smallest number of the ones mentioned)...so differences are probably insignificant. Definately not a bad dump either way.

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This means that the following ROMs can be REMOVED:

 

Congo Bongo (1983) (Sega - Beck-Tech) (006-01) [a]

 

and

 

Cookie Monster Munch (Cokie Monster's Maze, Cookie Monster's Garden) (Kid's Controller) (Children's Computer Workshop) (1983) (Atari, Gary Stark) (CX26102) (PAL) [a]

 

Still hesitate about removing one of the Commando Raids though.

 

All others stay in.

 

 

Commando and Cosmic Ark (PAL) are defenitely worth a closer examination.

 

These two could very well have had different releases (the starfield difference in Cosmic Ark NTSC comes to mind).

 

Perhaps Omegamatrix can have a closer look at these?

 

8)

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Cat Trax...

 

Nothing to get excited about, I'm sorry to say :(

The changes exist from $532C to $5335...

 

;"original"...
   STA	WSYNC ;3
   STA	VSYNC ;3
   LDX	#$00  ;2
   STX	COLUBK;3
   BIT	$87;3
   BMI	L5347 ;2

 

;[a]...
   LDX	#$00  ;2
   STX	COLUBK;3
   BIT	$87;3
   STA	WSYNC ;3
   STA	VSYNC ;3
   BMI	L5347 ;2

 

Identical code that basically does the same thing (the color black just being stored a scanline earlier).

Edited by Nukey Shay
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This means that the following ROMs can be REMOVED:

 

Congo Bongo (1983) (Sega - Beck-Tech) (006-01) [a]

 

and

 

Cookie Monster Munch (Cokie Monster's Maze, Cookie Monster's Garden) (Kid's Controller) (Children's Computer Workshop) (1983) (Atari, Gary Stark) (CX26102) (PAL) [a]

 

Still hesitate about removing one of the Commando Raids though.

 

 

Huh? Congo Bongo and Commando Raid are both "valid" alternates (i.e. feature changes that are not due to bad dumping). You wouldn't notice a difference when playing the alternate Congo Bongo...but it does do something different under the hood. Commando Raid has a visible change even tho only 2 bytes are involved.

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If the goal is just to remove bad dumps, yeah ;)

 

 

BTW Cosmic Ark (Reaction) moves around a little (but doesn't appear to be altered much), so that would indicate a different release. I need to comb through the 2 files to find out where symmetry gets thrown around (back and forth by a byte or two throughout the program!)

 

Commando just has a stretch of 28 bytes that change in the first bank only - looks to be raw data. Could be a hack instead of a dump of an actual cart.

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Hmmm.

 

If Commando [a] really turns out to be a post 1992 hack, then it doesn't belong in my collection.

 

It's dated 2003, btw.

 

The Cosmic Ark differences have nothing to do with the differences (starfield on/off) between the NTSC versions, right?

 

8)

Edited by Rom Hunter
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I dunno how that deal works even in the reverse-engineered file! :lol:

I'm a virtual amateur regarding display kernal tricks.

LOL

 

IIRC Rob Fulop said that even David Crane was fascinated by this trick.

 

Ok, but what about Commando?

 

Any idea what exactly was hacked?

 

8)

Edited by Rom Hunter
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Here was my post from a few pages back re: Commando.

 

I took another look at Commando with HOM3 (what a great tool!) and found a difference you may be interested in. The only change between the two versions is:

 

Commando (1988) (Activision, Mike Reidel) (AK-043-04).bin has a Data East logo and

Commando (1988) (Activision, Mike Reidel) (AK-043-04) [a].bin has a Capcom logo.

 

I can't figure out how to get either one to display in-game though.

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I always believed in ignoring the ram, but I'm at the point now where I say to Hell with the hotspots. I hope Stephena gives Thomas some auto detect bankswitching code from Stella and he can put something together to clean that up.

Just be aware that the auto-detect code in Stella isn't a 'magic bullet'. It's very dependent on data patterns in the ROM, but has only been really tested on current ROMs (ie, there's no guarantee it will work on newly dumped ROMs or any ROMs that use special/weird tricks). Note also that the code in Stella is GPL, so you're free to examine and modify it. But you probably won't be able to just take parts of it, as the ordering of tests (in the code) is also important. For those who are interested, the relevant code is in 'src/emucore/Cart.cxx'.

 

Also, I don't know if anyone realized, but there's currently a '-rominfo' commandline argument in Stella that runs a selected ROM for 30 frames or so, prints all auto-detected stuff (not just BS, but also NTSC/PAL, etc), then exits. Perhaps this will be helpful too??

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I can explain if you want me to.

 

By all means :) I dunno what you meant by HMM0 being stored "too early". Are HM's time-dependant?

 

 

BTW that is the only change in Cosmic Ark (Reaction)'s "original" and [a] files. The "original" fetches the color switch status and moves it into the enable position (5 bytes)...making the starfield selectable. The [a] version is always set to enable by loading an immediate value of 2 (2 bytes)...making the starfield non-selectable. That makes a difference of 3 bytes, which are filled with $FF before $1DD0.

 

 

Here was my post from a few pages back re: Commando.

 

Thanks for that. BTW the low 2 bits of $D2 select what text is to be displayed...

0 = ©1988

1 = Activision

2 = ©1986

3 = DataEast or Capcom (depending on version)

 

...but I haven't figured it out either. Here's a disassembly that I did to remove the offending scanline in the NTSC version if somebody wants to look at the problem:

Commando.zip

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By all means :) I dunno what you meant by HMM0 being stored "too early". Are HM's time-dependant?

Yes. The Stella Programmer's Guide even forbids changes to HM registers within 24 cycles after HMOVE. What happens if you change a value before, is pretty much unpredictable.

 

In Cosmic Ark an early change to HMM0 causes this unpredictable behavior, here resulting into endlessly repeated, multi-pixel movements of M0.

Edited by Thomas Jentzsch
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Ok, here's the fourth zip:

Don't get lost in the woods of Dragonstomper.

 

I didn't look at them yet...but didn't omega already do Crackpots (in the merged file he posted yesterday)?

 

Also, the [a1] file of Dragonstomper has the size of a preview game (9kb) instead of the full games it's named the same as (25kb). I'll compare it against those preview alternates if you want. Otherwise, the story would seem to be that it's just missing the rest of the game.

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Yeah...the [a1] file is very similar to the "original" preview file. I wish I knew more about handling Supercharger-specific disassemblies, but they are really out of my league.

 

The Difference between NTSC Dig Dug versions is in ram...the "original" file has values while the [a] version has them all = $FF (all 4 banks).

 

The difference between PAL Dig Dug versions is in the hotspots.

 

The difference between Double Dragon versions is also in the hotspots. Tho a couple banks set differing ORIGIN blocks between the 2 versions, this makes no difference to the 2600's 13-bit address line.

 

E.T. = hotspot value differences (yet again).

 

 

4 bad dumps total :)

 

 

The only difference between Dumbo versions is the timer values at $F02B and $F079. $35 and $2B in the "original" producing the correct scanline count of 312, they are both set to $20 in the [a] version (producing only 286). Neither one a bad dump.

 

I can pretty much only help you with the remaining non-Supercharger games, Dodge'Em and Crossforce, to discover their differences. Both need disassembly...but it's already clear that neither of them are bad dumps.

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So, correct me if I'm wrong:

 

Dragonstomper (Excalibur) (1982) (Starpath Corporation, Stephen Harland Landrum) (6) (AR-4400) [a1]

 

is actually similar to the other 9K 'preview' ROMs, but not identical.

 

Hence: it must be renamed and not removed.

 

 

However, these can be REMOVED:

 

Dig Dug (1983) (Atari - GCC, Doug Macrae) (CX2677) [a]

 

Dig Dug (1983) (Atari - GCC, Doug Macrae) (CX2677, CX2677P) (PAL) [a]

 

Double Dragon (1989) (Activision, Dan Kitchen) (EAK-050-04) (PAL) [a]

 

E.T. - The Extra-Terrestrial (1982) (Atari, Jerome Domurat, Howard Scott Warshaw) (CX2674) (PAL) [a]

 

 

All others can stay in

 

Right?

 

8)

Edited by Rom Hunter
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