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A Comprehensive Super Mario Bros. Disassembly

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Re: A Comprehensive Super Mario Bros. Disassembly

#61

Post by PyroLagus »

KGIII wrote: post #57

What is the goal of a project like this? I'm absolutely not meaning that as a pejorative. I am just curious if there's an actual goal here. Is the goal to make a faithful reproduction, historical reference, a hacking challenge, or? Is it just curiosity? I see lots of links in the thread, many for different games. Curiosity is as valid a reason as any other, but is there some sort of end result trying to be had? The v…

It has many uses really. It's a nice resource for learning assembly, especially 6502 assembly; it's a good reference for creating NES games, whether those are original titles or simply romhacks; it's also a great reference for building an emulator for the platform or a level editor for the game. And of course, disassembling a game and documenting the source code is a great hacking challenge that will leave you confident that you know asm. So, all the reasons that you listed, I suppose.

Re: A Comprehensive Super Mario Bros. Disassembly

#62

Post by KGIII »

PyroLagus wrote: post #61
KGIII wrote: post #57

What is the goal of a project like this? I'm absolutely not meaning that as a pejorative. I am just curious if there's an actual goal here. Is the goal to make a faithful reproduction, historical reference, a hacking challenge, or? Is it just curiosity? I see lots of links in the thread, many for different games. Curiosity is as valid a reason as any other, but is there some sort of end result trying to be had? The v…

It has many uses really. It's a nice resource for learning assembly, especially 6502 assembly; it's a good reference for creating NES games, whether those are original titles or simply romhacks; it's also a great reference for building an emulator for the platform or a level editor for the game. And of course, disassembling a game and documenting the source code is a great hacking challenge that will leave you confid…

I can also understand a 'just because' answer. I was just curious if there's a greater goal. I'm not a gamer but I do kind of pay attention to some aspects.

Re: A Comprehensive Super Mario Bros. Disassembly

#63

Post by jzl »

Ben Fry, the creator of Processing, created a beautiful visualization of the disassembled machine code of Super Mario Bros with arrows representing jump instructions:

http://benfry.com/dismap/mario-large2.jpg

via: http://benfry.com/dismap/

I've always loved this as a visualization of machine code. It's simultaneously amazing how complex it is and yet how simple it is when you consider that it represents the entire game all in one graphic. This is from 2007 I believe. I love that 10 years later the machine code is now fully annotated and understood.

Re: A Comprehensive Super Mario Bros. Disassembly

#65

Post by retSava »

jzl wrote: post #63

Ben Fry, the creator of Processing, created a beautiful visualization of the disassembled machine code of Super Mario Bros with arrows representing jump instructions: http://benfry.com/dismap/mario-large2.jpg via: http://benfry.com/dismap/ I've always loved this as a visualization of machine code. It's simultaneously amazing how complex it is and yet how simple it is when you consider that it represents the entire ga…

Wow, that is amazingly complex! It's beautiful, in a way.

I tried to see if there was something very central, called from lots of places, but there doesn't seem to be any such place. There are a few, but not something singular that stands out as completely dominant.

Long jumps get a more dominant visual appearance than short jumps. Would be interesting to see what it would look like with the address printed in size proportional to eg how many places call it, or how CPU intensive that subroutine is, etc.

Re: A Comprehensive Super Mario Bros. Disassembly

#66

Post by retSava »

retSava wrote: post #65
jzl wrote: post #63

Ben Fry, the creator of Processing, created a beautiful visualization of the disassembled machine code of Super Mario Bros with arrows representing jump instructions: http://benfry.com/dismap/mario-large2.jpg via: http://benfry.com/dismap/ I've always loved this as a visualization of machine code. It's simultaneously amazing how complex it is and yet how simple it is when you consider that it represents the entire ga…

Wow, that is amazingly complex! It's beautiful, in a way. I tried to see if there was something very central, called from lots of places, but there doesn't seem to be any such place. There are a few, but not something singular that stands out as completely dominant. Long jumps get a more dominant visual appearance than short jumps. Would be interesting to see what it would look like with the address printed in size p…

Also check out the other example dismap shows: Excitebike! Much fewer and longer subroutines. Interesting, I wonder if that in turn is mostly a result of developer coding style differences, or a result of game mechanics being different.

Re: A Comprehensive Super Mario Bros. Disassembly

#69

Post by thristian »

andyjohnson0 wrote: post #68

I'm not familiar with the history of this work, so I'll just ask. Is this the assembler code that was written by the original dev team, or were the comments reverse-engineered from a dissassembly of the game's machine code?

It's a "disassembly", so it's the work of somebody converting machine code back into assembler, and studying it long and hard to add comments, break out numbers into sensible-named constants, and choose decent names for loop labels. The original dev team was almost certainly not involved.

Re: A Comprehensive Super Mario Bros. Disassembly

#70

Post by andyjohnson0 »

thristian wrote: post #69
andyjohnson0 wrote: post #68

I'm not familiar with the history of this work, so I'll just ask. Is this the assembler code that was written by the original dev team, or were the comments reverse-engineered from a dissassembly of the game's machine code?

It's a "disassembly", so it's the work of somebody converting machine code back into assembler, and studying it long and hard to add comments, break out numbers into sensible-named constants, and choose decent names for loop labels. The original dev team was almost certainly not involved.

Thanks for the clarification. Given what you've said and the size of the thing, this is an awesome piece of work. The level of detail and perseverance required is enormously impressive.
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