Unix Pushes the 64-bit Envelope

Digital Equipment's Unix, IBM's OS/400, and Silicon Graphics' Irix are the only full 64-bit OS environments available today. Siemens' Reliant Unix (the merger of Siemens' Sinix and Pyramid's DCOSX) should ship by the end of the year.

Other OS vendors have opted for a piecemeal approach. For example, Sun's Solaris already supports 64-bit extended-precision arithmetic and large files, which can both benefit from CPU-specific instructions to speed up networking. You can expect Solaris to handle file sizes up to 1 TB in 1997 and to become a full-featured 64-bit OS in 1998, with a 64-bit kernel and 64-bit virtual addressing.

When will Microsoft deliver a 64-bit OS? Last June, the company promised that Cairo would support 64-bit very large memory (VLM) for applications needing more than the 4 GB of memory addressable with 32-bit systems. But the rollout of Cairo continues to be a fuzzy target (see "Unearthing Cairo").

VLM will most likely show up in Digital's Unix for 64-bit Alpha systems, which already can potentially provide 14 GB of addressable storage. This memory space will soon increase to 28 GB -- significant, but still a long way from an 18-billion-GB addressable with a true 64-bit OS.