Okay, here is my suggestion. Not given because I have the knowledge to execute it, but for someone else's benefit.

Normal sound card's purpose is to provide better sound; motherboards already know how to beep proficiently. The purpose of having a sound card in a calculator, rather, is to make it so the calculator can send a string of sound to the card, tell it what to do with it (like loop it), continue on it's merry way, until it feels like making a sound again, whereupon it sends to the sound hardware asking what it is doing, and deciding what to do with it. This suggestion is because one can make good sound (like mobileTunes), and good games (like greyscale 3D FPSs), but not at the same time. Also mobileTunes could use the sound card for background playing, almost like running two programs. Thoughts?

Go ahead and make one! Mail me a copy too!

What are your thoughts on the possibility and usefulness of such a thing?

I personally think that a sound card would be real cool, because it could take some of the weight of sound off the CPU, leaving the CPU for games and the sound card for music/sound effects.

It really wouldn't boost CPU performance, but you can add music without the cost of the CPU

Interesting idea, maybe one could send signals to an arduino via the I/O port. This could be done with the arduino itself or a special shield.

Sure you could build an audio coprocessor, but you'd be limited by the complete lack of hardware support for it. Most systems that are designed for decent-quality audio are designed such that the audio codec has direct memory access, so it can just be pointed at a region of memory and it outputs the PCM waveform therein.
In this case, you'd have to transfer all the data over the link port, which has no processing offload support, so you wouldn't be able to do anything else while streaming audio to it. Considering that limitation, you'd have to palettize the audio, for example by streaming all your samples to it, specify one to loop (as BGM), then send short messages to trigger mixing of other samples as necessary.

Well... GinDiamond I understand. I don't understand Tari, and I doubt GinDiamond does either, but that's okay. I knew I wouldn't understand. Anyway, I had two calculators, and listened to Tetris BGM on one while playing Tetris on the other; same goes for Mario, FZero, and so many others, and that is where this idea came from. And yes, it would send it through the link port, if need be, it might even have a sound card On/Off switch in the case, I don't know. That would be to disconnect the card from the link port.

Perhaps you mean something like this UARTunes project, a small external microcontroller that produces higher-quality sound while freeing the calculator's CPU to work on other things?

Exactly. However, doesn't the CPU need some of its memory and calculations to run the microcontroller?

In effect, you'll be adding sound, and although you'll be taking up some of the CPU, it won't (or shouldn't) be as costly as doing sound effects with the game (say, the DoodleJump app).

Yes, that is quite similar to what I had envisaged.

Yes, but higher-quality than mobileTunes would not be the goal. The goal would, yes, be to free up the calculator's CPU while the music was playing.

Well while were at it how about a speaker too! I dont understand all this tech-talk but a speaker would mean you would not need the I/O port after all right?

Right, but the speaker would probably be soldered to the I/O leads.
Right?

Perhaps or maybe a way around that could be found, I was just thinking that if one didn't mess with the I/O then it could still be used but who really uses it as a file transfer thingy anyhow? I still think its a really go idea, some people on this site need to get hired by TI might ensure we get the product we want.... starting to sound like we all need an iPad with unlimited space on it...

The I/O port is important for taking in raw info that the calc can understand (by cable, headphones, speakers, keyboards, link cables audrinos,whatever)

I'm not sure exactly what you're saying about I/O, but I can tell you that it's useable either as an audio port or a data port. If you want higher-quality audio than can be generated through simple PWM, you need an external DAC with associated microcontroller (or a microcontroller with built-in DACs) receiving data from the I/O port, which is exactly what the UARTunes project linked is.

I think it’s not the brightest idea, although it would rock. I’ve always envisioned seperate, attachable devices that could use a link port and then provide another that could do things like that, however... There is so much work that’d have to be done, it’d hardly be worth it, and so much would have to be written for supporting it.

It’d have to be a quite capable device all on its own.

Well considering we're dealing with a very limited core, it would probably be smartest to use representations of audio other than raw samples. A MIDI type interface for the calculator would drastically reduce the need for bandwidth. There's also nothing wrong with having several megabytes of RAM in any device you make, in which you could also preload PCM data and wavetables.

I, for one, use the I/O cable for data transfer, as my USB port is fried. So, pretty obviously, I'd be against permanent changes to the I/O port. I'm still totally OK with having a smallish device to plug in, though, that can perform certain functions, such as a sound card

you could make it to where at the start of a game or other program, you load all the sound files to the Card (requiring it to have some kind of memory) and simply have a "Start this song" sent to it. doing this would take up the CPU only during bootup of the program and sending those 'start' codes, but the card itself would be massive.