What I want to do with my TI-84 is make a program to play a game on it to run on its OS. It has a screen that could display OK grapics.....but I don't no where to start when programming a calculator.
The -84 doesn't have an "OS" -- it pretty much just has ROM like old '80's 8 bit computers did. this is actually to your ADVANTAGE because at it's heart the device is just a Z80 computer with 24k of RAM free after all the ROM (and video memory) is mapped into place. Some models have 128k chips inside them just because they were cheaper, that memory is inaccessible because the Z80 can only map 64k due to it's 16 bit address path. (16 bits addressing of 8 bits data = 64k limit) The thing does have BASIC built in, you want to write a game that might be a good place to start, and at a whopping 15mhz (which is SCREAMING fast for a Z80 -- TRS-80 Model 4 was only 6mhz) you should be able to do a good deal before having to resort to machine language -- But really if you want speed and lots going on, you're gonna have to break down and learn Z80 machine language and get yourself a decent cross-assembler. Generally speaking a cross assembler may be an easier place to start anyways, given that programming on the tiny display with the crappy calculator keyboard can be a bit... painful at times. Side note -- 96x64 graphics is indeed an interesting target, you might want to look at old Lo-res Apple II (40x48) and TRS-80 Model 1/3 (128x48) games for inspiration... You're talking even lower resolution than the 160x100 I've been playing with the past couple years.