What is meant by the term extended memory?
Extended memory refers to memory on an x86 platform PC above 1
Megabyte of memory.
In the Intel personal computer world, the original CPU was only
able to directly address up to 640K of memory. This was called
conventional memory. Above that, up to 1 megabytes, was called
expanded memory. Accessing the expanded memory required additional
instruction to allow for bank switching. You used special hardware
to "rename" sections (banks) of the expanded memory to something in
the conventional range so that it could be accessed as if it were
conventional memory.
Extended memory is memory greater than 1 megabyte for later
intel compatible x86 processors that could support it. Extended
memory was accessed using standardized API functions that allow
moving data to and from the memory area and management it.