This post is about processor input and output. Processor input and output units are responsible for moving in and out information to and from processor.

Any system (embedded/non-embedded, electrical, electromechanical, and other) can be connected to embedded processor as an I/O device. I/O devices can also be divided into smaller groups or input/output devices. Input devices/systems are providing data to the embedded system, output devices/systems are transmitting data from the embedded system. I/O devices/systems can be connected to the embedded system wireless/wired way or placed directly on the board.

Depending on the type of I/O device/system,  processor I/O components are divided into groups:

Real-time/ miscellaneous.

I/O hardware is usually consist of the following logical units:

Transmission medium;
Communication port;
Communication medium;
I/O controller;
I/O buses;
Master processor integrated I/O.

Processor I/Os are specifically grouped depending on the types of his I/O ports categories, that is also depending on the processor architecture, including hardware and software. Software also allows to group processor I/Os depending on it’s type. Hardware allows to group the I/O ports in serial, parallel or mixed types.

Big variety of embedded microprocessors can be found at Digi-Key Electronics catalogue.