Solaris development continued aggressively throughout the 1990s. Several key features distinguish Solaris from earlier UNIX implementations.
Symmetric multiprocessing — Solaris is implemented on systems ranging from single-processor systems to 64-processor symmetric multiprocessor servers. Solaris provides linear scalability up to the currently supported maximum of 64 processors.
64-bit kernel and process address space — A 64-bit kernel for 64-bit platforms provides an LP64 execution environment. (LP64 refers to the data model: long and pointer data types are 64 bits wide.) A 32-bit application environment is also provided so that 32-bit binaries execute on a 64-bit Solaris kernel alongside 64-bit applications.