HP Presario All-in-One CQ1-1000 - Desktop PC Getting Started Manual page 25

Understanding hard disk drive space
The hard disk drive on the Hewlett-Packard
and Compaq computers with the Microsoft®
Windows operating system preinstalled may
appear to be smaller than the size stated in
the product specifications, in the
documentation, or on the box. Hard disk
drives are described and advertised by
manufacturers in terms of decimal (base 10)
capacity. Microsoft Windows and other
programs, such as FDISK, use the binary (base
2) numbering system.
In decimal notation, one megabyte (MB) is
equal to 1,000,000 bytes, and one gigabyte
(GB) is equal to 1,000,000,000 bytes. In the
binary numbering system, one megabyte is
equal to 1,048,576 bytes, and one gigabyte
is equal to 1,073,741,824 bytes. Because of
the different measuring systems, you may see
a difference between the size reported by
Microsoft Windows and the size advertised.
The storage capacity of the hard disk drive is
as advertised.
Microsoft Windows reports smaller capacity in
the Windows Explorer tool and in the
computer window because it shows
information about one partition on the hard
disk drive at a time. One of the partitions
contains the System Recovery information.