Digital Input/Output is provided by a 6522 Versatile Interface Adapter (VIA).

The VIA offers us two 8bit ports, of which every line can be individually configured to be an input or an output. Four additional lines are provided, and these may be set to generate an interrupt if triggered.

Within Amélie, it is usual that port A is used as inputs (for sensing) while port B is used as outputs (for driving motors, relays, etc).

Also contained within the VIA are two 16bit timers. The first of these is configured to cause an interrupt at 50Hz (or every two centiseconds). This is used to maintain a system 'clock' and control various time-dependant things.

It should be noted that port A lines six and seven are reserved for the implementation of a basic I2C (or IIC) bus. This is provided to talk to an RTC/NVRAM part, as you can see in the picture.

The little circuit shown is a Philips PCF8583P. This can act as a real-time clock with 240 bytes of NVRAM, or as 256 bytes of NVRAM. Salvaged from an old VCR, this part happens to be the same as is used in the 'Archimedes' range of computers.
All that is missing from this circuit, and the big space on the board, is the battery - though there is no reason why two AA cells cannot be wired in (in a holder) with a diode to prevent accidental charging.