I'd like to share my MODs with fellow techno/trance fans and retro enthusiasts. They are made in Sound Club by Blue Moon Interactive. Let me know if you like anything.

https://modarchive.org/index.php?request=view_artist_modules&query=97143

What is an MOD?

https://modarchive.org/index.php?article-modules , linked from the Help menu at the top of the ModArchive UI, looks like a good introduction to the concept of modules / tracks.
While one can easily make large modules by using dozens of large samples, it's often possible to obtain minutes of decent to good quality music in a file of well under 1 MB, which is far less than MP3 files of decent quality, let alone losslessly compressed formats such as FLAC. All it takes is a playing program, which isn't necessarily a huge piece of code, especially if one restricts the support to the most popular formats: MOD, STM+S3M, XM, IT, (MPTM which goes even further wrt. capabilities and effects, it's a beast).
I somewhat disagree with one of the mod players listed on that page, though... I know that it's relatively popular, but last time I checked, mikmod had significant playing inaccuracies.

In short, mods are somewhat of a competition to MIDI. They depend on sampling.

The likes of MilkyTracker/Player and VLC media player can play the files. Blitz BASIC languages also had a built in MOD player for your games. Of all the MOD players, this is one of the best. It's awesome because adding MOD music to a game gives it a whole new feel.

The program I'm using is called SoundClub. It produces S3M (screamtracker mods) files and has a simple piano roll interface that is more intuitive than the average tracker interface in my opinion. Also, it has a DOS version which is cool because it allows you to track and play MOD music on DOS>

Another cool feature about Sound Club for DOS is that you can select many types of sound hardware including the PC speaker or OPL3. It actually renders from the PC speaker pretty well..

The TI84+CE has a CPU that looks similar in power to a 386. My 386 can play mods on DOS with Sound Club. I wonder if a MOD player/tracker can be made for TI...

You also mentioned MPT(Modplug tracker). That thing is SO USEFUL. It can convert between MIDI and MOD and supports so many versions of the format.

Up to 4-channel sound output on the legacy I/O port with proprietary 2.5mm stereo jack of older TI graphing calculators has already been achieved. For instance, Houston Tracker ( https://www.irrlichtproject.de/houston/ ) on newer models of the monochrome TI-Z80 series, or PolySnd ( https://www.ticalc.org/archives/files/fileinfo/311/31192.html ) on the TI-68k series.

Models which have only an USB port, such as your 84+CE, are less suitable for the implementation of arbitrary sound output.

Wow! I knew about playing mono music on the TI calc back in my high school days. There was a program that turned it into a "keyboard" as well as several programs that played music through the aux. I even remember their being a program to use loops to produce some FM radio signals to play music on a radio.

I never realized 4 channels was possible on the old TI calcs. Although, now that you mention it I remember this video. https://www.youtube.com/watch?v=I6G0CnBSWVk