Can someone help me examining the fixed version of Dodge 'Em?

[Rom Hunter]

Two versions of Dodge 'Em were released by Atari in both PAL and NTSC format.

The second version had a (bug?) fix, but to my knowledge nobody has found out what this fix actually does.

Can someone with enough coding knowledge find out what exactly has been fixed here?

Would very much appreciate it.

AFAIK it's the only fixed ROM that still carries a secret.

I attached the NTSC version (the original and the fixed one).

Cheers,

Rom

Dodge 'Em - Dodger Cars (Head On) (1980) (Atari, Carla Meninsky - Sears) (CX2637 - 49-75158) ~.bin Dodge 'Em - Dodger Cars (Head On) (1980) (Atari, Carla Meninsky - Sears) (CX2637 - 49-75158) [fixed] ~.bin

Edited December 14, 2022 by Rom Hunter

[Supergun]

This was one of the first 2600 carts that I “finished” so to speak as it has the “1084 perfect game max score auto end.”

 

Could the bug fix have been a modification that corrected this? (after all it basically just takes away your 3 lives even though you never crash and that’s what ends the game)

[Rom Hunter]

6 hours ago, Supergun said:

This was one of the first 2600 carts that I “finished” so to speak as it has the “1084 perfect game max score auto end.”

 

Could the bug fix have been a modification that corrected this? (after all it basically just takes away your 3 lives even though you never crash and that’s what ends the game)

There are more than one speculations about what this fix contains, but I need 100% proof.

Both versions are quite different, since new code and a new variable was inserted.

[Thomas Jentzsch]

Anyone else getting "Access denied" errors when trying to download the ROMs?

[+Al_Nafuur]

18 minutes ago, Thomas Jentzsch said:

Anyone else getting "Access denied" errors when trying to download the ROMs?

Me too

[Rom Hunter]

Me too.

 

Weird.

 

Anyway, they are both in my V17 collection (and also both PAL versions).

 

 

[Thomas Jentzsch]

I took a little bit of extra time to compare both ROMs. The effective differences are quite small, but it takes a time to analyze them.

 

As of now, I found one difference: When the game is over, the right car's color is changed from brown to green in the non-fixed version. Also, when switching B/W mode, the right car does not change color immediately in the fixed version. Both changes seem to go into the wrong direction for a fixed version.

[Thomas Jentzsch]

13 hours ago, Supergun said:

This was one of the first 2600 carts that I “finished” so to speak as it has the “1084 perfect game max score auto end.”

 

Could the bug fix have been a modification that corrected this? (after all it basically just takes away your 3 lives even though you never crash and that’s what ends the game)

Nope. Still there.

[Rom Hunter]

2 hours ago, Thomas Jentzsch said:

I took a little bit of extra time to compare both ROMs. The effective differences are quite small, but it takes a time to analyze them.

 

As of now, I found one difference: When the game is over, the right car's color is changed from brown to green in the non-fixed version. Also, when switching B/W mode, the right car does not change color immediately in the fixed version. Both changes seem to go into the wrong direction for a fixed version.

Interesting.

And the bug described on this page is also still there in both versions?
http://www.atarimania.com/game-atari-2600-vcs-dodge--em_18170.html

[JetSetIlly]

2 hours ago, Thomas Jentzsch said:

I took a little bit of extra time to compare both ROMs. The effective differences are quite small, but it takes a time to analyze them.

 

As of now, I found one difference: When the game is over, the right car's color is changed from brown to green in the non-fixed version. Also, when switching B/W mode, the right car does not change color immediately in the fixed version. Both changes seem to go into the wrong direction for a fixed version.

 

That's all I'm seeing too. Gopher2600's comparison tool highlights the difference (Fixed version on the large screen and the original version in the comparison window)

 

 

How did you spot this Thomas? Are you just inspecting the code or do you have a tool?

 

[Thomas Jentzsch]

31 minutes ago, Rom Hunter said:

Interesting.

And the bug described on this page is also still there in both versions?
http://www.atarimania.com/game-atari-2600-vcs-dodge--em_18170.html

No idea. How do you trigger that bug?

[Thomas Jentzsch]

21 minutes ago, JetSetIlly said:

How did you spot this Thomas? Are you just inspecting the code or do you have a tool?

I disassembled both ROMs using Stella and then manually converted the result into one common source code file (attached). Afterwards, the source code differences became minimal.

 

Using the FIXED assembler switch, you can create both NTSC versions from it. 

Dodge 'Em.asm

[Rom Hunter]

44 minutes ago, Thomas Jentzsch said:

No idea. How do you trigger that bug?

I have no idea.

It was discovered here:

[Rom Hunter]

I noticed that the PAL 'fixed' version only shows different colors after the game ends.

No differences in B/W mode.


 

Edited December 15, 2022 by Rom Hunter

[JetSetIlly]

4 hours ago, Thomas Jentzsch said:

Using the FIXED assembler switch, you can create both NTSC versions from it

 

I'm getting the access denied error for this file like the ROMs in the original post.

 

[Thomas Jentzsch]

11 minutes ago, JetSetIlly said:

I'm getting the access denied error for this file like the ROMs in the original post.

@Albert Can you help here?

[Albert]

4 minutes ago, Thomas Jentzsch said:

@Albert Can you help here?

Well, that's something I haven't seen before.  I will have to submit a ticket to have Invision look at it.  I also cannot download any of the attachments in this thread.

 

 ..Al

[Thomas Jentzsch]

@Albert I just tried to create a new thread to be able to post my attachment.  But I got the same problem there.

 

So it seems the problem is not local.

[+batari]

I wonder if one of the versions has a bug I found as a kid. We bought Dodge ‘Em when it was first released.

 

Normally you can move your car one slot while going fast or two when going slow. But as a kid I used to be able to move my car three slots at once occasionally. I have never been able to replicate that trick in the modern day. 

[Thomas Jentzsch]

22 hours ago, batari said:

Normally you can move your car one slot while going fast or two when going slow. But as a kid I used to be able to move my car three slots at once occasionally. I have never been able to replicate that trick in the modern day. 

It would be cool to find out how it worked. I suppose you do not remember any details?

[+batari]

3 hours ago, Thomas Jentzsch said:

It would be cool to find out how it worked. I suppose you do not remember any details?

Yeah, I recall it might only have worked for up or down, and I remember having to hit up or down at exactly the right time, maybe single frame timing.

 

I have never seen any other reports of others experiencing the same thing so I’d wondered if my console had an issue until today when I saw there may be two versions.

 

Or, I wondered if it was an effect that only works on consoles and not emulators, such as if joysticks are only read once a frame and not continuously as they are on A console. 

 

 

 

 

[Keatah]

Tried D'L the roms and the filenames were messed up.

[+batari]

Downloads may be fixed - they both worked for me?

[Reality Studio]

On 12/25/2022 at 4:38 PM, batari said:

I wonder if one of the versions has a bug I found as a kid. We bought Dodge ‘Em when it was first released.

 

Normally you can move your car one slot while going fast or two when going slow. But as a kid I used to be able to move my car three slots at once occasionally. I have never been able to replicate that trick in the modern day. 

I remember that happening as well playing it as a kid but it was rare, never did figure out how to do it.

[+batari]

2 hours ago, Reality Studio said:

I remember that happening as well playing it as a kid but it was rare, never did figure out how to do it.

I am glad to hear someone else experienced this, as this gives more evidence to it being a bug in the game rather than something with my console.

 

I kind of remember bring able to replicate it several times back then. Certainly not every time, but sometimes if I pulled the joystick up or down just right I could do it. Though I do recall pulling "harder" than normal to get it to work, though knowing today that the CX-40 is just a digital stick, this doesn't make much sense.