Product manual

Breaking the 137GB Storage Barrier
A-4 Maxtor MaXLine Plus II 250GB AT
leaving that space empty.
The BIOS companies will also have to perform some work to recognize the increased
capacity of the devices attached to the bus and allow the extended 48-bit commands
to pass on to the devices. Boot partitions will also be an issue for the capacity of the
drive if the BIOS does not recognize the 48-bit addressing scheme at or before the
system boots the OS from the hard drive.
Independent software driver efforts for legacy operating systems (Windows NT 4,
Windows 98, and so on) will need to be implemented to allow higher-capacity
devices to work on installed systems and recognize the maximum available capacity
of the drive over the 137-gigabyte limit.
A.1.6 What is the Next Barrier?
While it is true that the ATA/ATAPI-6 standard defines a method to provide a total
capacity for a device of 144 petabytes, the next limit will be imposed not by the ATA
devices but by many of the popular operating systems in use today. This limit will be
at 2.2 terabytes (2,200 gigabytes). This barrier exists because many of today’s
operating systems are based on 32-bit addressing. These operating systems include
many flavors of Linux, Mac OS 9.x, and Windows 95, 98, ME, NT 4, 2000, and XP
(Windows XP/64-bit also has the limit because of leveraged 32-bit code).
This barrier could be real as early as 2004 if current hard drive capacity rate increases
continue along the same growth trends.
Appendix A: Terminology
• BIOS: (an acronym for Basic Input/Output System design): The BIOS
processes and redirects all data as it is being accessed and stored.
• FAT: (an acronym for File Allocation Table): The FAT tells the
computer where data has been stored on the hard drive.
• CHS: (an acronym for Cylinders, Heads, and Sectors): The basic layout
components of a hard drive. INT 13h & INT 13h extensions: protocols
used for accessing data on hard drives.
Appendix B: Big Numbers
• 131 kilobytes = 131,000 bytes
a little more than 30 pages of text
• 33 megabytes = 33,000,000 bytes
more than 8,000 pages of text or 25 300-page books
• 137 gigabytes = 137,000,000,000 bytes
more than 100,000 books, or the contents of a good library
• 2.2 terabytes = 2,200,000,000,000 bytes
almost 2,000,000 books, or the about content of the Library of Congress
• 144 petabytes = 144,000,000,000,000,000 bytes