All computers: You'll need a computer with a USB port, a compatable calculator, and a USB cable to connect the two. Calcsy works with the TI-84+, TI-84+ Silver Edition, and the TI-89 Titanium calculators. I don't believe it will work with a TI-84+ Color calculator, but I can try to make it work if you send me one! Your calculator may have come with a USB cable that can connect your calculator to your computer. If you don't have one, you just need a USB A to mini B cable. This relatively cheap AmazonBasics USB cable will work, but any one will do.
Mac OS X: You will need to use Mac OS 10.5 (Leopard) or higher.
Windows: Sorry, a Windows version is not available yet, but one will be forthcoming. Windows USB drivers are somewhat difficult to work with, and I need to get time to develop a proper installer.
Linux: A Linux version may be made available as time permits. Packaging and testing are the holdups here.
Troubleshooting / FAQ
Calcsy can't find my calculator
Double-check the requirements above, and then triple-check to make sure that everything is plugged in firmly. Sometimes you have to push the USB cable pretty hard into the calculator before it's actually connected. Also note that you need to use the USB port on your calculator: the silver "TI Connectivity USB Graph Link Cable" with what looks like a headphone plug on one end will not work. (If you need a USB cable that will work, Amazon sells them.)
Calcsy quits unexpectedly
Calcsy closes automatically when it loses a connection to the calculator, which is ideally only when you unplug the calculator. If Calcsy is closing when you haven't unplugged the calculator, try unplugging the cable from both ends and plugging it back in firmly. If that doesn't work, try a different USB cable.
My calculator seems slow when Calcsy is running
Your calculator is trying to send its screen to Calcsy at the same time it is responding to your input. Sometimes, this makes the calculator appear a bit slower, especially if you are used to pressing buttons very rapidly. Unfortunately, there's not much Calcsy can do about this. If you are a bit more deliberate in pressing buttons, hopefully any slowness will not be as noticeable.
Calcsy doesn't update while my calculator is graphing (or busy)
The TI-84+ and TI-84+ Silver calculators do not respond to communication via USB while they are "busy" (most often while graphing, or in a loop in a program). Calcsy can't do anything about this, but it will start displaying the screen when the calculator starts responding again.
Calcsy shows the wrong calculator
Sorry, Calcsy only supports one calculator at a time right now. Make sure you only have one calculator plugged into your computer at a time when running Calcsy to avoid confusion.
Calcsy doesn't start
That's interesting. Calcsy should either tell you that it can't find a calculator or show the calculator's screen. Double-check the Calcsy requirements above, and if everything seems in order but Calcsy still isn't working, get in contact with me and give as many details as you can (operating system and version, computer model, calculator type, and so forth).
The Calcsy website design was inspired by Hadley Wickham's website.