Japan · decommissioned · hpc

CP-PACS

Also known as Hitachi SR2201/2048

Operated by University of Tsukuba at Tsukuba Center for Computational Sciences .

Phase 1 seed dataset, compiled by hand. These rows were built from public operator, laboratory and vendor sources. A mechanical second-reader pass has since fetched every cited source: 1092 of 1153 systems have a readable citation that names them, and 40 are genuinely weakly sourced. Every claim carries its source and a confidence tier. Treat anything below verified as a lead, not a citation.

Measured performance

Rmax: 368.2 GFlop/s
Rpeak: 614.0 GFlop/s
Rmax ÷ Rpeak: 60.0%
Cores: 2,048
Power: -
Per watt: - GF/W

Figures are as last publicly reported for the configuration described below, not a live measurement. Where a system was upgraded in place, the post-upgrade configuration is shown and the earlier one appears in the timeline.

What this machine is made of

One row per supplier relationship. “Supplier at build” is the company that shipped the part at the time; where that company has since been acquired, the parent it rolls up to today is shown beside it. That distinction is what makes ticker-level aggregation possible across a thirty-year dataset.

Role	Part	Supplier at build	Quantity	Confidence	Source
Integrator	- Hitachi SR2201	Hitachi 6501TSE	-	Verified	museum.ipsj.or.jp netlib.org
CPU	Hitachi SR2201 processing unit CPUs PA-RISC 1.1 · 1C · 0.15 GHz Hitachi SR2201 PU	Hitachi 6501TSE	2,048 reported	Verified	museum.ipsj.or.jp netlib.org
Interconnect	Hitachi 3D hyper-crossbar Interconnect 3D hyper-crossbar · 300 MB/s point to point 3D hyper-crossbar	Hitachi 6501TSE	-	Verified	netlib.org museum.ipsj.or.jp
Storage	Distributed RAID 5 disk array Storage Direct-attached, no separate metadata server · Hundreds of GB, era-dependent 529 GB distributed disks in RAID 5 configuration	Hitachi 6501TSE	-	Verified	museum.ipsj.or.jp netlib.org
Cooling	Air cooling (CRAC/CRAH) Cooling Room-level air handling · Practical ceiling around 15-20 kW per rack multichip module now with fins for air-cooling	Hitachi 6501TSE	-	Reported	arxiv.org
Operating system	Hitachi HI-UX/MPP Operating systems Unix (Mach 3.0 microkernel), Hitachi-customised · Proprietary HI-UX/MPP	Hitachi 6501TSE	-	Reported	museum.ipsj.or.jp top500.org

The read

A university machine at the top of the list, which has not happened since. Tsukuba had been building the PACS/PAX series since the 1970s and co-designed CP-PACS with Hitachi, so the SR2201 that Hitachi then sold commercially carries technology developed for a physics department. The processor is Hitachi’s own implementation of HP’s PA-RISC with pseudo-vector hardware bolted on, which is a licensing arrangement the parts table has to represent as design nationality separate from instruction-set origin. It ran for nine years, retiring in September 2005.

Timeline

1991 Announced source
1996-10 First operational source
1996-11 List debut at #1 (November 1996) source
2005-09 Decommissioned source

Public list appearances

Pointers only: rank and edition, linking to the canonical entry. We do not reproduce list tables. See sourcing policy.

#1: TOP500, November 1996 →

Site & facility

Tsukuba Center for Computational Sciences

Location: Tsukuba, Japan
Commissioned: 1996

museum.ipsj.or.jp netlib.org

Source check

We fetched this system's own citations and recorded whether each page actually mentions it. This is a corroboration signal, not a fact check, and it is published so you can see how well the sourcing holds up rather than take it on trust.

Cited source	Result	Found on the page
museum.ipsj.or.jp	names system, part and count	Hitachi SR2201 processing unit, Hitachi 3D hyper-crossbar, Hitachi HI-UX/MPP, Distributed RAID 5 disk array · counts: 2048
netlib.org	names system, part and count	Hitachi SR2201 processing unit, Hitachi 3D hyper-crossbar, Hitachi HI-UX/MPP, Distributed RAID 5 disk array · counts: 2048

Checked 2026-10-09 by pnpm verify. Re-run it and the table changes with the web.