<architecture> A term describing a computer architecture based
	around an {ALU}, {registers} and {data bus} which are 64
	{bit}s wide.

	64-bit processors were quite common in 1996, e.g. {Digital}
	{Alpha}, versions of {Sun} {SPARC}, {MIPS}, {IBM} {AS/4000}.
	the {PowerPC} and {Intel} were expected to move to 64 bits at
	their next generation - {PPC 620} and {Intel P7}.

	A 64-bit {address bus} allows the processor to address 18
	million {gigabytes} as opposed to the mere 4 gigabytes allowed
	with 32 bits.  There were in 1996 already {hard disks} which
	can hold over 4GB.  Floating point calculations can also be
	more accurate.

	A 64-bit {OS} is needed as well to take advantage of the CPU.
	In 1996 there were only a few 64-bit operating systems,
	including {OS/400}, {Digital} {Unix}, {Solaris} (partialy).  A
	32-bit OS can run on a 64-bit CPU.

	(2004-05-12)