So, I know that you can change the 6x8 font on the TI-83+ using the font hook, but is changing the font on the TI-89 possible? (I only need to edit the 6x8 font.) If so, how do you do it in C?

Thanks for your help!

tiosmod's documentation makes a reference to one of the available patches being to hardcode the standard fonts, so apparently there is a way, though I've never seen or heard of anyone using it for some reason. I always assumed it wasn't possible as a result. I know nothing about it, unfortunately. Hopefully someone knowledgeable sees this.

Thanks for pointing me to the topic, tev

It is, indeed, possible to redefine the fonts
* if you want to permanently redefine the font, the most efficient way is to change section 2b of tiosmod+amspatch (which is, as the rest of that program, poorly documented), and as a bonus, benefit from the other improvements made by tiosmod+amspatch;
EDIT: more precisely, at the end of the 2b section, you'd write the binary data of your font through Seek(F_4x6_data), Seek(F_6x8_data) or Seek(F_8x10_data), then PutByte in a loop

* otherwise, you can use the attribute system to redefine them (attributes 0x300, 0x301 and 0x302), in either a TSR ASM program or a FlashApp.
TSR ASM programs are a pain, unless you depend on HW3Patch / tiosmod+amspatch; FlashApps also are a pain if you're running Windows Vista or newer: TI's severely outdated SDK doesn't run well on anything newer than Win XP, due to the dependency on Microsoft's non-standard JVM (which is very hard to find, at that).

Hardly anybody ever used the font redefinition support, because TI's font drawing routines are very slow: it's easy to make a custom DrawChar that is an order of magnitude faster than the DrawChar in AMS 2.xx and 3.xx... Therefore, basically everybody who needed custom fonts just embedded them into the program and used custom drawing routines.

Hope that this helps

So, on AMS 3.10, where is this section?

If you're talking about "section", I take it that you're talking about tiosmod+amspatch. This week, I don't have the relevant files with me, so the best I can do is to point you at the source code available from https://github.com/debrouxl/tiosmod ...

If you embed the font data as hex arrays into your patch, all you have to do is described into my previous post: for each modified font, Seek, then PutByte in a loop

You can choose to view books in either small or large font size.When you open a book, the TI-Reader App displays the text inlarge font by default.
Small and large font sizes are available at fontvilla only if both large andsmall fonts are selected when the file is converted using theTI-Reader Converter.
ress ƒ2. In the FORMATS dialog box, on the Font Size option, selectLarge or Small, and press Enter¸