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Thread: NES tape drive??? Need tech info!

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    ServBot (Level 11) davidbrit2's Avatar
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    Default NES tape drive??? Need tech info!

    Okay, I think I might be on to something here. You know how Excitebike, Wrecking Crew, and Mach Rider have the Save/Load features in the editor? And how everyone assumed for years that they do nothing because it was originally for the FDS? I've noticed something that suggests this is not the case.

    Try this:
    Fire up any NES game with an editor and Save/Load options. Make some basic level design. Now, turn the volume on the TV up quite a bit and hit Save. Hear that? If you've ever played Supercharger or C64 tapes through an audio cassette player, you should recognize this instantly. It's actually saving the data via an encoded audio stream! You can hear a lead-in signal (probably around 2200 Hz or so) for a few seconds, followed by the actual encoded data.

    So now the real question: how do we get the data back in to the NES? The Famicom had an actual microphone input from the controllers, so I have no doubts that there's some way to do this. I suspect that the audio input lives somewhere on the expansion connector underneath the NES. The problem is that I'm not familiar enough with the chips on the NES board to know which line I should be poking at. Has anybody ever figured out which pin on the connector corresponds to the audio input? If not, I'll just connect one wire to ground on the board, and try playing back a recorded stream into each pin sequentially, but I'd like to be a bit more scientific about it first.

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    drowning in medals Ed Oscuro's Avatar
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    Default Re: NES tape drive??? Need tech info!

    Intereeeesting, dollars to dimes the tape format for the AES version of the NES used this.

    I doubt the NES has the circuitry to do this, though the FC might have...well, I don't know that much about electronics, maybe it does. You'd need some sort of tape deck with automatic leveling for it to work worth beans, otherwise you'd see problems with loading like folks had on the C64 and Spectrum.

    Oh yeah, you da MAN, David! :)

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    drowning in medals Ed Oscuro's Avatar
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    Default Re: NES tape drive??? Need tech info!

    Okayy, second thought.

    Does the Pols Voice trick on Zelda no Densetsu just figure out volume, or does it track tones..? If all the mic is doing is closing a circuit at a certain volume threshhold, it might not have enough tech. Well, that's a thought.

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    Banana (Level 7) davidleeroth's Avatar
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    Famicom had tape drive available among other things and maybe they didn't bother removing the feature from the NES version. As to how to make it work on the NES, I have no idea.

    "I never should the games I sold and I have replaced them but they are not the game just a hollow shell of the same game." -RugalSizzler

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    ServBot (Level 11) davidbrit2's Avatar
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    Yeah, from what I've read, the internal hardware of the NES and Famicom are mostly identical, except for the pinouts of the controller ports/expansion port and such. So if there was a chip capable of handling an audio input, such as from a microphone or tape drive, I'm assuming the audio input pin is still floating around somewhere in the NES. And I suspect it leads to somewhere on that big expansion port. But where... Heh.

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    Wow, you have to turn the TV sound WAY up to hear it on Excitebike. I remember hearing something back in the day i think when saving on Mach Rider. This is interesting.

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    ServBot (Level 11) davidbrit2's Avatar
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    Definitely. I haven't found any pinout info for the expansion connector yet, so I might just start probing pins on it with an audio input and see what happens. I kind of wonder if the encoding/decoding is handled in software, or if it's a hardware function of the SPU or something. Hmm... You know, something like setting a starting location and byte length, then executing a specific SPU function that "plays" the RAM segment, and then just have the program wait until it gets an interrupt back from the SPU or something. Any NES emu/homebrew developers care to comment?

    Oh, someone do me a favor. Load up any one of these three games on a bootleg Famiclone with built in multi-cart and see if you get the same result when "saving". If the audio stream doesn't appear, we can pretty much assume it's handled in hardware.
    EDIT: Actually, now that I think of it, it would probably be the Japanese version ROMs, which are less likely to have tape drive saving, seeing as they were FDS games to begin with. But it's still worth trying to see what happens anyway. :-)

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    drowning in medals Ed Oscuro's Avatar
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    Quote Originally Posted by davidleeroth
    Famicom had tape drive available
    An actual tape drive, for use with Nintendo Basic? Hmm...

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    Ryu Hayabusa (Level 16) rbudrick's Avatar
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    An actual tape drive, for use with Nintendo Basic? Hmm...
    Aww, you beat me to it, Ed!

    Come to think of it...I think I remember reading something about this in an Issue of the Japanese publication Backup Technique (basically the console hackers Bible...now known as Game Lab since the early 90s). It is a thick book that came out quarterly I think. I have all but issues 1, 19, and 21...I wish I could remember where I saw something like that. I know there was a crapload of Famicom Basic programs in those books.....damn.

    -Rob
    The moral is, don't **** with Uncle Tim when he's been drinking!

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    Pac-Man (Level 10) FABombjoy's Avatar
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    Some of the technical documents I've read on the Famicom Disk System describe it's operation as similar to a tape drive except it's recorded in a spiral fashion around a disk. If you've ever watched the behavior of a FDS, it never randomly seeks & always begins a load or write command by seeking the outside of the disk and moving inward (or vise-versa, don't remember exactly)

    It's conceivable that when the games were ported, the cartridge version simply had the FDS hardware checks NOPed out so a cart will blindly perform write commands to whatever memory space the FDS used. You could compare disassemblies of the FDS version to the NES ROM and find out for sure.

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    ServBot (Level 11) davidbrit2's Avatar
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    Quote Originally Posted by FABombjoy
    Some of the technical documents I've read on the Famicom Disk System describe it's operation as similar to a tape drive except it's recorded in a spiral fashion around a disk. If you've ever watched the behavior of a FDS, it never randomly seeks & always begins a load or write command by seeking the outside of the disk and moving inward (or vise-versa, don't remember exactly)

    It's conceivable that when the games were ported, the cartridge version simply had the FDS hardware checks NOPed out so a cart will blindly perform write commands to whatever memory space the FDS used. You could compare disassemblies of the FDS version to the NES ROM and find out for sure.
    Hmm, very interesting theory... I'm not sure that I'm totally convinced that this is the case, but I'm certainly open to evidence here. Heh. I'd really like to see a good analysis of disassemblies so that we can figure out just what is going on.

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    ServBot (Level 11) hydr0x's Avatar
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    hey there

    i have various docs on the SNES so i could help with that, but obviously you need NES

    did you try your luck on #snesdev ?? i'm pretty sure those guys could help you
    -Jan

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    Track down Kevin Horton. Absolutely your best technical support guy you can get.

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    ServBot (Level 11) hydr0x's Avatar
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    Quote Originally Posted by portnoyd
    Track down Kevin Horton. Absolutely your best technical support guy you can get.
    if i'm not mistaken he's on #nesdev too
    -Jan

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    ServBot (Level 11) davidbrit2's Avatar
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    Quote Originally Posted by portnoyd
    Track down Kevin Horton. Absolutely your best technical support guy you can get.
    Is that the fellow that goes by "kevtris"? If so, I'll be sure to accost him.

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    Quote Originally Posted by davidbrit2
    Quote Originally Posted by portnoyd
    Track down Kevin Horton. Absolutely your best technical support guy you can get.
    Is that the fellow that goes by "kevtris"? If so, I'll be sure to accost him.
    You would be correct. Also try talking to memblers from NESworld, between the two of them, if there is a way to do this, and by god would it be sweet, they will make it so.

    dave

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    ServBot (Level 11) davidbrit2's Avatar
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    Yeah, it would be pretty neat to trade Wrecking Crew, Excitebike, and Mach Rider levels over the internet via audio files. I mean, sure, you could just swap emulator save states, but that isn't half as cool. Ha ha.

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    Peach (Level 3)
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    I can picture it now... "My level even SOUNDS better then yours."

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    ServBot (Level 11) davidbrit2's Avatar
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    Quote Originally Posted by XxMe2NiKxX
    I can picture it now... "My level even SOUNDS better then yours."
    Shh, don't give Paul Slocum any crazy ideas. ;-)

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    Interesting. I never noticed this before.I would always fiddle with the save/load thing in Excitebike, but I never thought to turn the sound up!

    Anybody think it might be as simple as hooking up a tape recorder to the audio-out on the side of the system? Really. To save, you hit record on the recorder and then hit save in the game. To load, hit load in the game and then play the recording.

    Of course, this is assuming you can get an audio-in from that jack, which is probably dead wrong. Still, I wouldn't overlook the possibility.

    Then again, and I know I'm going to post something not provable and equates to nothing more than an urban legend for everyone other than myself, but one time at Funcoland, maybe 2000, I saw some sort of NES memory card drive there. Why didn't I pick it up? There were no cards. I still kick myself for not getting it, though. I'd never seen anything like it before and haven't seen anything like it ever again. All I know is that I saw it, and it exists. I don't think it was a Famicom thing or a third party thing either. It definitely looked like an official Nintendo thing. Oh well. Don't believe me. I don't blame you.

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