{66} Doing Z80 IO ?? CLAIM YOUR BONUS BYTE !!!

The Z80 has a clear I/O advantage over the 8080 and 8085 when it comes to utilizing every last feature of the IN and OUT instructions. Where the 8080 and 8085 simply duplicate the port address onto the high address byte, the Z80 outputs the contents of a register to the high address byte. This allows the designer and programmer to output an extra data byte with each input or output instruction. Combine them to create a 16-bit port address, 16-bits of additional data, or output a byte simultaneously with an input byte.