The TIOS is the official, standard operating system for the TI-83+ series of calculators (including the TI-83+ and TI-84+ and the respective Silver Editions of each). The vast majority of programs for such calculators run on top of the TIOS, or on top of some subsidiary program that runs from the TIOS, and thereby implicitly depend on its functionality. However, some people have researched writing alternative operating system code and sending it to the calculator to replace the TIOS. Several such alternative operating systems are available on the Web, though most of them are not yet at a production stage of development.
List of alternative operating systems
- CEPTIC, by Michael Vincent: a Control and Execute Program for TI Calculators. The current version of CEPTIC only runs on the TI-83+ SE, but can be modified to run on the TI-83+. Assembly source is available, but actually using the OS in its present state is considered non-practical, and the project has been discontinued for various reasons.
- PongOS, by FloppusMaximus: a simple, proof-of-concept system whose namesake feature is an embedded Pong game. Some other system utilities, mostly inspired by Dan Englender's Calcsys, are also available in PongOS, including a hex editor, memory mover (with flash capability), flash sector eraser, and port monitor. Link support is not provided.
- Vera, by several members of different programming groups: dubbed the "true calc lover's OS". Vera is intended to consist of a very basic kernel which can be easily extended to include desired features. The original Vera project has been abandoned, but it has been picked up again in a different form, and seems to be progressing nicely.
- CSX, by Sean McLaughlin: a command-line-based operating system with a screen layout similar to that of the TI-89 calculators. CSX provides a simple filesystem, send and receive of files over a link cable, hex editing of memory, and running of Z80 machine code programs.
- Nostalgy, originally by XDG Kat-Productions, now developed by Reaktix Software: an unofficial project started by XDG Kat-Productions, abandoned when the two main developers became involved in other projects, and later resumed by Saibot84. A pre-alpha working demo is available. Development is still underway, albeit extremely slowly. It currently features a task-switching environment inspired by Radical Software's TSE, although linking and a file system are not yet implemented.
- LIFOS, by Peter Marheine: a similar project to Vera, designed to offer minimal functionality (linking, memory management, and machine code execution) in its basic incarnation but meant to be easily extended into a near-seamless infrastructure of various functions. Currently (5-28-07) in early alpha stages. The name comes from the memory allocation system (LIFO OS, or LIFOs).
- BAOS, by Erik van 't Wout: Basic Assembly Operating System. (excerpt from the ReadMe:) Being developed "to be a real Operating System for TI-83+ based calculators. It should turn your calculator into a real computer, which can be used for mathematical purposes, but not as main target. Additional functionality should be easy to implement trough the use of libraries."
- OS2, by Brandon Wilson: OS2 is "the TI-OS done right", a from-the-ground-up re-implementation of the TI-OS, designed to do everything the TI-OS can do and run everything it can, but with fewer restrictions and changes not normally possible due to the TI-OS' structure, such as being able to run BASIC programs directly from the archive. It also supports dual-booting with the TI-OS so a user can continue to use the original TI-OS while more and more is added to OS2. Currently only dual-booting and a basic system monitor are supported.
- XOS by Luc Bruant aka fullmetalcoder, XOS main targets are SE calcs (those with 128kb of RAM). It aims to provide a lot of power to application developer, larger storage capacity whenever possible and a minimal emulation layer to ensure a certain level of backward compatibility of TIOS programs and Apps so as to ease the transition for users.
- KnightOS by SirCmpwn: a completely different OS designed loosely around Linux. KnightOS has no compatibility with the TIOS and completely clobbers the TIOS's filesystems. KnightOS uses its own filesystem, KFS, which uses the ROM for storage and uses RAM entirely for program execution and the heap/stack. The kernel, KnightKernel, also has thread support. However, KnightOS has not been released. It is still under development.
- GlaßOS, by AHelper, is an OS written for the TI84PSE in C. It features a working USB driver; system-provided libc commands provided by sdcclib, such as floating point math, printf and friends, and others; GUI, graphics, and grayscale libraries; and more: all written either completely or mostly in C. Because of a radical approach, the OS provides no support for TIOS and is simple a core OS with no stand-alone functionality (packaged programs can be installed). The source of GlaßOS has been released and is stable to run on a calc. A final release date is pending.