Just 160x240 mode and/or scrolling (for now, anyway)

What's the range of x,y? 0-63?

Actually, for the wrapping around, I'm referring to having a window of (y1,y1+height-1) and (0,319). If you draw vertically, you'll wrap around after 319 (not undocumented at all). However, from what I saw on the SVN, you may not be clipping LCD coordinates to 8-bits or 9-bits upon write. Any bits listed as 0 in the data sheet is forced to 0 (i.e. writes are ignored). This should be useful for some code optimizations, I think.

Data can be displayed in either direction, but displaying vertically will likely be easier due to only needing 8-bit coordinates for the output window. Also, displaying vertically is pretty much a must for games that abuse horizontal scrolling if the sprites are going to wrap around GRAM properly.

Does the push bc \ pop bc get auto-optimized or something?

Yep, that's exactly what happens. If you draw tiles offscreen before you reach them, you can pretty much scroll infinitely in the horizontal direction.

I keep wondering, what exactly is a "frame" here. I mean, if all you're doing is changing the scroll registers you can probably get over 9000 FPS, but that doesn't really affect the display which has its own frame rate.

Note that the scrolling in that video doesn't involve drawing any pixels, by the way. It'll be a bit slower if you want to have a play area wider than two screen widths, since you'll have to actually draw in the new tiles. Should still be relatively fast, though.

Can I take this as a stab at the built-in TI-Nspire 84+ emulator?

Well, this error is something even more basic than that, by which I mean the file failed to open at all. Perhaps you should try running makeapp.exe directly and typing in the full filepath of your ROM file.

Yep, you can choose any 160-pixel wide area of the screen and extend it.

Well, the partial display window output positions should always be 0 and 160 due to how the display interlacing works, but the GRAM that you display can be any 160 consecutive columns, yes. (You can even wrap around from the right side to the left side of GRAM, which means horizontal scrolling tricks are still possible.)

I was just messing around with the LCD controller and I enabled interlaced mode, and it was different than I expected, in a good way. It basically outputted the first 160 columns of GRAM on the even columns of the LCD and the last 160 columns of GRAM on the odd columns of the LCD. Combining that with partial images produced magic

I just made an awesome discovery. It's possible to effectively halve the horizontal resolution of the screen on the TI-84+CSE, while still filling up the entire area of the screen, which means asm game programmers can double their framerate at a small visual cost.



This will even allow for double-buffering, where you draw to the offscreen area and then swap it in instantly, preventing flickering. My method uses partial images and interlaced output.

More detailed information on how to implement:
Enable two partial images, where one is displayed at column 0 and the other is displayed at column 160. Both partial images should be set to the same 160 columns of GRAM which you want to display. (When enabling the partial images, disable the base image.) Then turn on interlaced output (bit 10 of register 1).

They're the exact same format as 8xk as far as we can tell, but they have a different signature only accepted by the 84+CSE. The extension difference is so users can easily tell the difference.