64 bit

architecture A term describing a computer architecture based

around an ALU, registers, and data bus which are 64

bits wide.

64-bit processors are quite common in 1996, e.g. Digital

Alpha, versions of Sun SPARC, MIPS, IBM AS/4000.

the PowerPC and Intel are 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 are 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 1986 there are 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.

(1996-12-23)