ITecture> A term describing a computer archITecture based around an ALU, 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-bITaddress 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-bITOS 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)