A term describiNg a computer architecture based arouNd aNALU, registers aNd data bus which are 64 bits wide. 64-bit processors were quite commoN iN 1996, e.g. DigitalAlpha, versioNs of SuNSPARC, MIPS, IBMAS/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 millioNgigabytes 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, DigitalUNix, Solaris (partialy). A 32-bit OS caN ruN oN a 64-bit CPU. (2004-05-12)
