gameboy dev

Discussion in 'Other Handhelds' started by justinwalker, Jan 18, 2016.

  1. justinwalker
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    justinwalker Newbie

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    My question is if it's possible to redesign the gameboy ds with a similar processor and have it be able to run the games. I wanted to hack the original gameboy and create my own PCBs with specs similar to the gameboy ds but the processor is specially designed for nintendo which means I cant buy it anywhere and there is no datasheet available for it. I could take one of the processors off of an old board but I still have no data on it like pins, registers, ect. How hard would it be to complete this project and is it possible?

    The processors in the ds lite are ARM7TDMI and ARM926Ej-s. I have found similar processors to these and so is it possible to run a game on one of these similar but not exactly the same processors?
     
  2. FAST6191

    FAST6191 Techromancer

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    You are jumbling up all sorts of terms there (not least of all gameboy ds which is meaningless, or confusing at very best) and I am not quite sure what you mean.

    Can you clone the hardware and have it run original carts? I have not yet seen it for the DS but the GBA ( http://www.k1gbasp.com/ ), NES and countless other consoles have this. I see no reason why you could not do 99% of things done on the DS with a hardware clone.

    You do not need to have original chips, they are fairly normal reference designs when all is said and done and we know basically everything about them down to timing level
    http://problemkaputt.de/gbatek.htm has lots of good stuff.
    http://imrannazar.com/ARM-Opcode-Map

    "similar but not exactly the same processors"
    That will depend entirely upon what has changed, and might even vary with software (there are all sorts of edge cases and uncommon things, http://arstechnica.com/gaming/2011/...-3ghz-quest-to-build-a-perfect-snes-emulator/ has some discussion on some of the things like that for the SNES, and you might wish to look around various emulator wikis/faqs for things there, in the case of the GBA I believe Golden Sun's sound is rather demanding.).

    How hard? We see small teams make consoles all the time, I imagine it would scale pretty well there. I do not know what you have done previously but at a gut level if you are asking the sorts of questions you are asking here then it is probably not going to be easy for you.
     
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  3. justinwalker
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    justinwalker Newbie

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    Ok, thank you for the great examples, that was exactly what I was looking for. I was just worried that doing a hardware clone wouldn't be possible because I read that some of the unique instructions were added for the processor. But now that I think about it if the cpu architecture is the same then they should match up I suppose. I'm an engineering student and was looking for a fun project to show off to people and sense most people are into gaming anyway it seemed like a good idea. I plan to put the cloned gameboy into the original gameboy case and have it be able to play games up to the nintendo ds console.

    — Posts automatically merged - Please don't double post! —

    I was also reading about the new console design that looks pretty cool. It has a curved screen like those new curved ultra hd tvs that are out now except the console is convex instead of concave.
     
  4. FAST6191

    FAST6191 Techromancer

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    Thinking back through things we tended not to see most consoles have extra functionality baked into the silicon of the CPU. As a co-processor (be it onboard or on cart a la NES mappers or SNES special chips) or as BIOS/firmware functions then sure and I could give you loads of examples (the specs docs people use for the hardware and to refine emulators like those I linked go into great detail for a lot of them) but not baked into CPU silicon. Some lost functionality (usually that which was more concerned with business/industrial uses -- BCD is not so useful in a NES, prior to the rise of floating and fixed point though it was pretty essential for fractional numbers) or altered things slightly but it is not like you might have seen for some of the custom ARM stuff out there now. Sure I would hate to replicate the N64 (look up N64 microcode if you want some fun) but for anything you are sitting there thinking "well that is a fairly standard embedded processor... I wonder" then it is probably feasible.
    http://problemkaputt.de/pandocs.htm#cpucomparisionwithz80
    https://courses.cit.cornell.edu/ee476/FinalProjects/s2009/bhp7_teg25/bhp7_teg25/

    Said extra stuff is often well within the realms of a moderately priced modern FPGA or CPLD as well, though have fun powering that. If they were extra instructions and you tried to bolt it on then you would probably run into latency, race conditions and bus issues, assuming you did not do some crude version of dynamic recompilation*/instruction translation anyway.

    *the classic example might be from the assembler worlds -- most instruction sets will probably not allow you to stick an immediate in there the same size as the instruction (can't move a 32 bit immediate in an instruction that is 32 bits itself sort of thing) but your assembler will probably handle this all for you. Most extras would not be basic RISC design but with a crazy SIMD instruction or something as much as just a better divide or something.


    "I plan to put the cloned gameboy into the original gameboy case and have it be able to play games up to the nintendo ds console"
    Practically speaking I would probably get something that runs some version of android as the emulators for all of this do well. Slightly less practically the DS might be hard but simple 16 MHz ARM chips are doable in FPGA these days. I do also hear interesting things coming out of China as far as baking your silicon goes (lots of the old and past their prime processes, though processes still measured in nanometres and certainly smaller than anything the GBA era and backwards people would have available to them, are available for reasonable prices to the general world similar to the opening up on the PCB manufacture market some 10-15 years ago).

    Other than the android thing* then whether I would head down that path I am not sure. That said something I have long wished to say to several clone device makers is perhaps consider making a better device -- clones tend to end up with the photocopy of a photocopy problem where trying to beat it from the outset gets better results.

    *be careful if you use flash carts as they can work different ways but we have seen several devices dump games and saves into memory and feed that to an emulator, before writing it all back. I would say such a thing would be a more suitable project for a final year project or a masters thesis.