2.5 5.5 November 1995 December 2003 First to support UltraSPARC and include CDE, NFSv3 and NFS/TCP. Dropped sun4 ( VMEbus ) support. POSIX.1c-1995 pthreads added. Doors added but undocumented. [ 42 ] 2.5.1 5.5.1 May 1996 September 2005 Only release to support PowerPC platform; Ultra Enterprise support added; user and group