TI-83 Simulator

You can run a virtual TI-83 on your computer using Texas Instruments' debugger program. Here's how:

1 - Visit Texas Instruments' web page to download the installer file.

2 - Download and save TI-83 Plus SDK

3 - Restart your computer and run the program TI-83 Flash Debugger. An icon should be on your desktop.

4 - To access the virtual calculator do the following:
                     -  Click File --> New --> Ti-83 Plus 
                     -  Click Debug --> Go
                     -  Click View --> Calc on Top

Now you have your very own graphing calculator on your computer! 

These same instructions with helpful screen grabs can be found here.