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Ikrananka

[Solved] Miner 2049er Rom Differences

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I just dumped three Miner 2049er carts - all in Micro Fun cart shells and with identical gold labels - however I get two different dumps. One of the cart dumps matches a Coleco (Canada) Miner 2049er cart dump while the other two carts are different but match each other. Now, these two dumps do exist in the public domain with one being shown as an alternate dump with the label [a]. Comparing the two different rom files shows that the number of different bytes is significant, at 956. What is interesting is that the alternate rom has all of the 60, 61, and 62 byte values replaced correspondingly with 70, 71 and 72 - there are no other changes. Playing the title screen etc. and the first level of the game I could discern no difference in gameplay, sounds or speed between the two roms.



So, it would appear that there were two versions of this game commercially released. However, I can't help but wonder which one was the first and which was the second release.



I also wonder what the effect of the byte changes would be and so am hoping that someone might be able to shed light on this.


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This sounds like developers reassembled the ROM changing the RAM location $6000-$63ff to $7000-$73ff

 

This would not affect gameplay.

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Now it makes me wonder what we would find by dumping the Victory variants?

Apparently, the NTSC version were corrupt.... Does the 2 different variants has been dumped?

 

I must admit I hate this game to death, so I never even bothered to play Victory on CV

I only remember my friend receiving this game for his birthday back then....and we never figured out to play

make sense since we played it using regular controller... :lol: ... How stupid! :P

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This sounds like developers reassembled the ROM changing the RAM location $6000-$63ff to $7000-$73ff

 

This would not affect gameplay.

 

Thanks nanochess - great insight. Can you think of any reason why they would have changed RAM location? Just seems odd that they would do this part way through production unless there was a very good reason for doing so.

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Thanks nanochess - great insight. Can you think of any reason why they would have changed RAM location? Just seems odd that they would do this part way through production unless there was a very good reason for doing so.

 

Probably to insure compatibility with the ADAM computer. Using RAM outside the $7000-$73ff range is what made Super Cobra incompatible with the ADAM.

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Probably to insure compatibility with the ADAM computer. Using RAM outside the $7000-$73ff range is what made Super Cobra incompatible with the ADAM.

 

Ah, so then is it likely that the $6000-$63ff version was the first to be released but was then changed to the $7000-$73ff version in the later releases. If that is the case, then the "main" rom file should be the $7000-$73ff version while the "alternate" rom file should be the $6000-$63ff version - agreed?

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Ah, so then is it likely that the $6000-$63ff version was the first to be released but was then changed to the $7000-$73ff version in the later releases. If that is the case, then the "main" rom file should be the $7000-$73ff version while the "alternate" rom file should be the $6000-$63ff version - agreed?

 

That sounds logical to me. :)

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Thanks nanochess - great insight. Can you think of any reason why they would have changed RAM location? Just seems odd that they would do this part way through production unless there was a very good reason for doing so.

 

I think that they worked out the game and after publishing it they saw the official Coleco documentation stating the official $7000 location for RAM or they had a problem in ADAM.

 

I don't know if the game uses Coleco BIOS routines but as Pixelboy said, using the $6000 location could made it to fail in ADAM.

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Spoke to soon - I still have questions!!!!

 

I thought I'd try and test the rom file compatibility in the only ADAM emulator that I can get to work on my Windows 7 PC, i.e. Virtual ADAM 1.03. Both versions of the Miner 2049er rom file work in Virtual ADAM with no apparent problems. Is this because Virtual ADAM isn't memory range limited in the same way a real ADAM would be, or is it that the ADAM is not that sensitive to the $6000 versus $7000 RAM start issue? How should/would the problem exhibit itself if I for instance had a real ADAM and tried to play the $6000 version of the cart? Are there specific circumstances where the problem would occur?

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Okay, an explaination is in order here: The architecture of the ColecoVision allows for 8K of RAM, but to cut costs, Coleco only put 1K of RAM in the console, positioned at $7000-$73ff within the main addressing range. The other 7K within the allowed 8K range are mirrors to that 1K of RAM. So if the game software writes a value at $6000, it's actually written at $7000 within the console hardware.

 

When a CV cartridge game runs on the ADAM, the ADAM's native 24K of RAM is used by the software. This means that there's no mirroring involved: If you write at $6000, you're NOT writting at $7000.

 

With Miner 2049er, if all the used RAM addresses fall within $6000 and $63FF, then it doesn't matter if the RAM is mirrored or not. On a ColecoVision $7000 to $73FF will be used, and on the ADAM $6000 to $63FF will be used, and the game software itself isn't aware of the difference.

 

The reason why Super Cobra doesn't work on the ADAM is because RAM usage is a mess, a mess that works on the ColecoVision because of the mirroring.

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