There is a book entitled "Microprocessors" on Google books. In chapter 8, the book defines "Memory and I/O Interfacing". You can read the related pages from here.
Also, this article defines Memory Interfacing and I/O Interfacing. The following is an excerpt from the article:
While executing an instruction, there is a necessity for the
microprocessor to access memory frequently for reading various
instruction codes and data stored in the memory. The interfacing
circuit aids in accessing the memory.
Memory requires some signals to read from and write to registers.
Similarly the microprocessor transmits some signals for reading or
writing a data.
But what is the purpose of interfacing circuit here?
The interfacing process involves matching the memory requirements with
the microprocessor signals. The interfacing circuit therefore should
be designed in such a way that it matches the memory signal
requirements with the signals of the microprocessor. For example for
carrying out a READ process, the microprocessor should initiate a read
signal which the memory requires to read a data. In simple words, the
primary function of a memory interfacing circuit is to aid the
microprocessor in reading and writing a data to the given register of
a memory chip.
We know that keyboard and Displays are used as communication channel
with outside world. So it is necessary that we interface keyboard and
displays with the microprocessor. This is called I/O interfacing. In
this type of interfacing we use latches and buffers for interfacing
the keyboards and displays with the microprocessor.
But the main disadvantage with this interfacing is that the
microprocessor can perform only one function. It functions as an input
device if it is connected to buffer and as an output device if it is
connected to latch. Thus the capability is very limited in this type