The MIO, Multiple Input Output Board, was designed to meet all Input/Output
requirements of most 8080 System users by providing the User with the
following Input/ Output interfaces:
A Data Storage interface to a standard audio cassette
recorder;
Two Parallel Input/Output (PIO) ports;
One Serial Input/Output port; and
One control port to be used for internal and external control functions.
As an example of its versatility, a single MIO Board could control a TV
Typewriter, a Line Printer, a Teletype, and a cassette recorder
The manual for this board can be obtained
here
and
here.