Category:84PCE:OS Information

Use this category for information applicable to both the TI-84 Plus CE and the TI-83 Premium CE. For information only applicable to the TI-83 Premium CE, see the relevant category.

Information:

• TI has included the Zilog eZ80 C runtime library.
• There are different signing keys for TI-84 Plus CE and TI-83 Premium CE models.
• Matrices operations now limited to matrices with no more than 400 elements, whereas before the TI-83 series didn't have enough RAM for that to be a problem.
  • This is apparently because they take too long, but you can still ask to sort a 999 element list.
• Because the eZ80 doesn't need paging, apps are no longer limited to being allocated in 16 K increments, and they contain a relocations table like TI-89 apps
  • The app signing key is now 2048 bits
  • TI can now develop apps using C; and we can do programs.
• The interrupt handler now saves and restores IY, so you can use IY depending on what OS routines you want that may depend on IY.
• The boot code interrupt handler checks that MBASE is set to D0 before passing interrupt handling control to OS. If it's not D0, the boot code jumps to some kind of error handler that basically resets the calculator. So unless you're handing interrupts yourself, or disable interrupts, you can't change MBASE to get a full 64 K of Z80 mode code and data in whatever location suits your program. (However, you can still simply place your Z80 mode code in safe RAM locations in the first 64 K of RAM.)
• The boot code interrupt handler also disables mixed-memory-mode, so you can't run code in Z80 mode without disabling interrupts or handling them yourself.