Epson ActionNote 4SLC/33 User Manual page 49

All memory in a computer is managed using addresses-
numbers that describe the location of each byte of data. Each
memory chip must have its own set of unique addresses so that
the operating system knows where to store and find data.
Conventional memory is memory that MS-DOS recognizes and
manages directly. The size of conventional memory is limited
to 640KB and has addresses in the range 0 to 640KB.
Reserved memory is memory in the range 640KB to lMB. The
system enhances its performance by using 128KB of this
memory as shadow RAM, and the remaining memory is
available.
Extended memory is memory with addresses in the range 1MB to
8MB, and is used only by the following:
Certain operating systems, such as OS/2
Some MS-DOS interfaces, such as Windows
Some RAM disk programs, such as VDISK
Some hard disk caching programs, such as SMARTDRV
Certain specially-written MS-DOS applications.
2-18 Using Your Computer