6 Analogue Outputs (PWM), which can switch something ON and OFF thousands of times per second, allowing effects like dimming a light or control the speed of a motor.
And 2 hardware serial ports. One of them is used to communicate to the computer via the USB. It also provides ISP10 and i2c11 Interfaces, so it's possible to connect i2c sensors which are becoming very popular or create a network of devices. [Barragán, 2005]
Fig. 46 Wiring I/O Board diagram [source: ibid]
The fact that the Wiring I/O board has 40 Digital pins was essential. With these pins I could at least drive a 6x6 LED matrix without the use of any additional circuit. The next step was to start dealing with electronics.
Fig. 47 Wiring I/O Board circuit schematics [source: ibid]
10 In-System Programming, a way to configure programmable logic devices while they are installed in a larger system [sourse: Wikipedia].
11 I²C (for Inter-Integrated Circuit, pronounced I-squared-C) is a serial computer bus invented by Philips. The original system was created in the early 1980s as a simple internal bus system for building control electronics with various Philips chips. Today it is used to connect low-speed peripherals in an embedded system or motherboard. [sourse: ibid].
Using Everyday Objects as Communication tools