In practice, most physical connections between a processor and external devices
use multiplexing. Doing so allows the processor to transfer arbitrary amounts of data
without devoting many physical pins to the connection. In the next section, we will
learn how multiplexing also improves CPU performance.
To summarize:
Multiplexing is used to construct an I/O interface that can transfer
arbitrary amounts of data over a fixed number of parallel wires. Multiplexing
hardware divides the data into blocks, and transfers each
block independently.