1. TI-80: The first middle-school graphing calculator.
2. TI-81: My (and TI's) first graphing calculator (01991).

1. TI-82: Graphing calculator enhanced for statistics use.
2. TI-83: Updated TI-82.  This one is playing a game called Turbo Breakout (not very well, though).

     

1. TI-83 Plus: Newest version of the TI-83.  Upgradeable with Flash technology.  Mine has a nifty red (of course) cover and is showing here the results of a numerical integration program. 
2. TI-85: My second graphing calculator (01993) and still my primary working and teaching machine. A close reading of the screen will reveal this this calculator breaks the 69! barrier by accepting numbers up to 10¹⁰⁰⁰.

1. TI-86: Updated version of the TI-85.
2. TI-89: The functionality of the TI-92 in the TI-8x platform.  This particular one is also overhead-projection compatible for easy classroom use.

1. TI-73: TI's second middle grades graphing calculator.  This has some nice statistical capacities as well as full fraction operations.
2. TI-73 Explorer: In 02003, the TI-73 was re-released in a merger with TI's popular line of Explorer calculators for classroom use.

1. TI-83+ Silver Edition: Introduced in 02001, this calculator is an enhanced TI-83+ with more memory and a faster processor.
2. TI-83+ Silver Edition Overhead projector model: This calculator is equipped for overhead projection and combines the power of the Silver Edition with the keyboard of the original TI-83+.
3. TI-83+ Ultra Violet edition: This variation on the TI-83+ was sold in America through Target department stores in 02002.  A "Cool Blue" version had been released through Target in 02001.  Functionally, this calculator is the same as a standard TI-83+.

TI-84+ Silver Edition: In 02004, TI introduced three new graphing calculators, basically ramped-up versions of earlier models.  This one is an enhanced TI-83+ SE with more memory for applications and a faster processor--also a new shape.

TI-92: The first TI calculator with a computer algebra system and 3-D graphing capacities.  I use this one with an overhead projection panel in the classroom.

Voyage 200: The latest (02002) product from TI, this Personal Learning Tool adds a graphical interface, clock, and several other new capacities to the TI-92+, while refining and streamlining the shape somewhat.

1. Casio fx-7000G: The first graphing calculator.  This one is showing my favorite function,
f(x) = e^{tan(ln x)}, on the interval (0,100).
2. Casio fx-7000GA: Second generation Casio, showing f(x) = e^{tan(ln x)} on the interval (0,10).
3. Casio OH-7700G: A graphing calculator designed for overhead projection.  On permanent loan from the Albion College Department of Mathematics.

1. fx-7700G: The line is extended further, including a more natural set of cursor keys.
2. CFX-9850G Plus: A color graphing calculator (one arena where Casio has taken a lead and not been challenged), this one can display results in blue, orange, and green, as is seen here with graphs of f(x) = x, g(x) = x², and h(x) = x³.

Not yet pictured: Casio Color Power Graphic CFX-9850G, TI-83+ Cool Blue Edition, TI-89 Titanium.