Hitachi announced the 840PS and 850PS UNIX servers in April 1995 as its 3500 series cluster server models. The models began shipping in November 1995. Equipped with Hewlett-Packard’s PA-7200 PA-RISC processor (100 MHz and 120 MHz), the 840PS and 850PS supported scalable systems that could be expanded up to eight nodes (32 processors) by connecting nodes (each expandable up to four processors) with a high-speed HS-Link switch (320 MB/s, fully redundancy).
The 840PS and 850PS maintained API and ABI compatibility with 3500 series/3050RX group models so that existing applications could be run without any modifications.
They also allowed power-supply units to be connected or disconnected on a node or expansion module basis.
