So an on-and-off interest I've had over the years is programming/running games/ultilities/etc. on graphics calculators! Because it's a real shame to drop $100+ on a graphing calculator for school (what the heck, TI?!?) and then just use it for calculating, especially if you're like seventh-grade me and somehow convinced your parents to spring for the extra-expensive colour version. Seriously, I can't remember how I did that, but somehow fenagled myself something that could play GameBoy games---more on that later---at potentially a lower cost than or similar cost to an actual GameBoy. I think my town's Office Depot (RIP) had them on sale? But yeah, this isn't a huge hobby, mostly just a passing interest sometimes, but I decided to give it a page anyways because it's my site and I can do what I like. ANYWAYS, yeah, graphics calculators are cool.
Here's the trusty friend who's helped me through five years of math classes, the ACT and even an AP exam: my TI-84 Plus CE! Obviously, if they'd had a purple colour at the time, I would've gotten that one, but they didn't, so I went with pink. Anyways, it actually only has a few megabytes of internal memory---128kb of RAM and 3mb of "archive" ROM, which you can only access with some programes but which can't be wiped by a reset. The left picture above shows the calculator running Cesium, one of the most popular shells for the CE, which can run all programs and "apps" (TI-sponsored programs that can do more complex stuff, i.e. one of them does spreadsheets), even archived ones. It's also, as you can perhaps see, customizable by colour! And has some basic file-managing capabilities.
And, because this is the Net and literally everything is on here, there are some TI hobbyist forums! My favourite by far is Cemetech. It has a forum, and evan an IRC chatroom (!), and tonnes of downloads for games, as well as utilities, for various calculators! I've downloaded most of my favourite programs for my calculator from here.
Anyways, I digress. Here are my favourite TI-84 Plus CE programs!
Finally, a quick PSA for anybody interested in specifically the TI-84 Plus CE: do NOT upgrade your OS past OS 5.5!. OS 5.5 and later add very little functionality and remove the ability to run Assembly and C programs. From what I've heard, TI is adding features that have been around for a while to the "what's new" on their Web-site to encourage users to upgrade, thereby forfeiting their ability to do with their calculators what they please. And their replacement is a bad Python implementation only available on new models, and that's slower than any other calculator implementation. Thankfully, there's a jailbreak for newer calculators to run Assembly, but it's still a jerk move from TI, and better safe than sorry.