The ATmega128 microcontroller has seven general-purpose input-output (I/O) ports: Port A through Port G. An I/O port is a collection of pins, and these pins can be individually configured to send (output) or receive (input) a single binary bit. Each port has three I/O registers, which are used to control the behavior of its pins: PORTx, DDRx, and PINx. (The x is just a generic notation; for example, Port As three I/O registers are PORTA, DDRA, and PINA.)

1. Suppose you want to configure Port B so that all 8 of its pins are configured as outputs. Which I/O register is used to make this configuration, and what 8-bit binary value must be written to configure all 8 pins as outputs?

2. Suppose all 8 of Port Ds pins have been configured as inputs. Which I/O register must be used to read the current state of Port Ds pins?

3. Does the function of a PORTx register differ depending on the setting of its corresponding DDRx register? If so, explain any differences.