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Hack question

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#1 summer86 OFFLINE  


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Posted Mon Jan 14, 2019 11:04 AM

Hi everybody,


I was wondering how hard would be to hack an 2600 Atari game,

in order that once in a while when playing a photograph (just for a second) 

would appear in the screen?





#2 R.Cade OFFLINE  



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Posted Mon Jan 14, 2019 11:37 AM

The 2600 can't display anything resembling a "photograph" without a lot of talented hacking. Are you wanting to create Polybius?

#3 summer86 OFFLINE  


    Combat Commando

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Posted Mon Jan 14, 2019 3:05 PM

Thanks R.Cade :)


is anyone around able to do that?

It's for an artistic project and open to collaboration!



#4 azure OFFLINE  


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Posted Tue Jan 15, 2019 4:52 AM

What you're asking for is extremely difficult. Displaying any photograph on an Atari 2600 is a major undertaking, because the system doesn't natively support bitmapped graphics beyond two 8 pixel wide sprites. It can be done, but it requires a combination of sophisticated techniques and tricks, and the result is sub par with a blocky and pixelated result.


The second issue is which game?  If it's an original game released in the 70s or 80s, there is no source code. The game would have to be disassembled and commented instruction by instruction by hand. Variables and subroutines would have to be identified, understood and named. That is a difficult multi-week or multi-month undertaking depending on the complexity of the game, the experience of the developer, and how much free time they have. Most of us are working on this part time, so we might have anywhere from 4 to 20 hours per week to work on projects. The best option would be selecting a game that's already been disassembled and commented, but that list is very short.


The third issue is does the game have enough remaining ROM space for inserting a photo and the accompanying code for rendering it? Space is limited so just about every 2600 game consumes all or most of the available ROM space. Half of the development process involves weeks or months optimizing and shrinking code so that more features can be squeezed into ROM. Every developer wants to pack their game with the most features possible, so they aren't going to leave blocks of ROM going unused.


The fourth issue is does the game have enough remaining RAM space? Many 2600 games use all the RAM, so extracting a single byte could require rewriting parts of the game that have already been through several rounds of optimization for space reduction.


The fifth issue is with the memory model of the game. Is it 2k, 4k, or 8k bankswitched or higher? Converting a 4k game to a bankswitched game is not a simple process. It requires decisions such as: Do I need one kernel for all banks? Should I use a different kernel for each bank? Can I move subroutines to another bank? Can I share subroutines between banks? Does this kernel need speedy access to data in another bank? Which subroutines and data must be duplicated in each bank? Answering these questions requires extensive analysis and deep understanding of how the game works. Simply adding another bank is not enough. The easiest option would be choosing a 2k game and expanding it to a 4k, but have you seen many 2k games? The original 2k titles were very simplistic and not that appealing next to 4k games that came out later.


The sixth issue is time and motivation. What's in it for the developer? It may seem like an easy task for someone unfamiliar with the Atari 2600's internals, but making simple things happen on the 2600 is not simple. Is there a compelling reason for someone to spend months working on your project? I wouldn't, because I don't have enough time for my own game. In addition to working on a game, I've been spending time on several partially implemented projects that will never be posted online. I have a text file containing 17+ game concepts I'm thinking about for my next game. Maybe one of those will get implemented, but I have to be choosy, because I'll be living with it for 6 to 18 months. I'm also investigating interesting graphic effects that could be used as the basis of a game. I've been a lurker since 2008, but I've only begun to get involved in the late spring of 2018. I'm positive the experienced developers doing this a lot longer have considered and discarded thousands of concepts and hundreds of unfinished projects. There isn't enough time in a life to accomplish all things we want to do on this platform.


Atari 2600 development is really time consuming, and it's an uphill struggle every step of the way, so I'm skeptical you're going to find someone interested.

#5 Thomas Jentzsch OFFLINE  

Thomas Jentzsch

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Posted Tue Jan 15, 2019 6:17 AM

I did something similar for a Planet of the Apes hack (Revenge of the Apes).

#6 SpiceWare OFFLINE  



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Posted Tue Jan 15, 2019 8:59 AM

You might find the Atari 2600 Hacks subforum to be useful.

#7 accousticguitar OFFLINE  



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Posted Tue Jan 15, 2019 1:15 PM

Iirc there was a game called 21 Blue that had pictures in it.

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