One of the most important features of the TI graphing calculators is their linking, where they communicate with another TI calculator or a computer across a link cable that is connected between them. There are a few different link cables that TI has created, and they each have their own advantages and disadvantages:
- Graph Link — This is the classic link cable that has been around since the TI-83 was first released. It works with every calculator before the TI-84+CE, and it comes in black (for the PCs) or gray (for the Macs). It works with the Graph Link software, which doesn't work very well with the newer calculators. The TI-84+CE no longer has an I/O port so this cable cannot be used to transfer data.
- USB Link — This is the new link cable that is designed to be much faster, since it uses the USB port of a computer rather than the COMM port that Graph Link uses. Besides the port, it also only works with the TI Connect software instead of the Graph Link software.
- Mini USB Link — This is only available on the newer TI-84+/SE calculators, since it actually uses the second smaller USB port on the TI-84+/SE calculator instead of the usual I/O port. It works pretty much the same way the USB Link does, and in fact uses the same TI Connect software.
In addition to the official link cables, you can also make your own using parts of other cables. Putting together a link cable is a rather delicate operation, and requires a considerable amount of knowledge of electronics and linking. This isn't recommended unless you know what you are doing — if you screw up, you can really mess up your calculator!
There are two commands that you can use when linking one calculator to another: GetCalc(, and Get(. The GetCalc( command was designed such that you can receive a variable from another calculator; unfortunately there are very specific requirements for the sending calculator to actually send the variable (it must be in a preemptible state like Pause or Menu(, and cannot be executing an assembly program). Whilst this can seem a difficult task to actually create a fully functional and fun multiplayer game, the multiplayer page shows workarounds to make such a program achievable — the key to which is fully understanding the nature of GetCalc(.
The Get( and Send( commands were created for use with the CBL (Calculator-Based Laboratory) and CBR (Calculator-Based Ranger) devices in math and science classes. These devices collect real-time data from various sensors that you can connect to them, and allow you to view and analyse the results. At the same time, they were originally used by the TI-82 calculator for receiving and sending variables respectively between calculators, and actually still operate in that capacity.