Various links to useful resources elsewhere!

Official Stuff


TI published an official software development kit for the 83 Plus long ago, but tend to pretend it never existed these days. Fortunately, the documentation still exists and can be easily browsed on the Internet Archive.

  • The SDK Guide describes the overall system architecture.
  • The System Routines Reference documents many of the available bcalls, but not all of them (presumably because TI didn’t intend the undocumented ones for use outside of the OS).
  • Some additional unsupported documentation was provided, documenting other interesting system parts that TI didn’t bother writing the documentation for themselves.


The creators of the Z80 processor, Zilog, of course provide their own documentation for how the processor works. Many of the details aren’t important if you’re simply writing software for it, but is helpful as “word of god” for what the CPU should do (though it’s not always correct!).


WikiTI is the premier community reference resource for all TI calculators. Things that TI have documented are mostly not covered on WikiTI, but it has a huge amount of reverse-engineered hardware and OS documentation.

While communities of calculator programmers have waned in the decades since the devices were first introduced, there are still some active ones:

  • is one of the oldest calculator web sites that continues to exist, with a large number of programs, some discussion and documentation.
  • Cemetech has an active discussion forum and community mostly centered around calculators but also other adjacent topics. Also has a copy of the new-defunct United-TI forums.
  • TI-Planet is another active forum and community, with more of a French-speaking and European focus.
  • CodeWalrus is a newer forum and community with significant overlap between it and others.

What’s this “GNU” All About, Eh?