While the Arduino family of boards connect to your computer using a USB virtual serial port, the ATmega ones have an actual serial connection on-board.

Here’s the code we promised you in the current issue of Macworld. To download a Zip archive containing this code as well as the compiled script, click here. long MINUTES = 15; // take a break ...

It would be fun to test however, and I think it wouldn’t be too hard to hit at least 115,200 bits per second coming in over serial and being pushed out over the parallel port with the current setup.