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 helpfully included the Zilog eZ80 C runtime library for us. Well, for them, anyway.
• The OS now has C code in it
• Different signing keys for TI-84 Plus CE and TI-83 Premium CE models, to prevent cheating in America
• Matrices operations now limited to matrices with no more than 400 elements, apparently because they take too long, whereas before the TI-83 series didn't have enough RAM for that to be a problem. (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
  • And it doesn't matter anyway, because they do not currently plan to release an SDK
  • The app signing key is now 2048 bits
  • TI can now develop apps using C
• 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 (which, you'll recall, you're not allowed to do), you can't change MBASE to get 64 K of Z80 mode code and data in whatever location suits your program.
  • So TI freed up one global register, just to take dibs on another one, and this time, no workarounds allowed!