Cray CS6400

However, the CS6400 adopted the XDBus packet-switched inter-processor bus also used in Sun Microsystems' SPARCcenter 2000 (Dragon) and SPARCserver 1000 (Baby Dragon or Scorpion) Sun4d systems.

Other features shared with the Sun servers included use of the same SuperSPARC microprocessor and Solaris operating system.

However, the CS6400 could be configured with four to 64 processors on quad XDBusses at 55 MHz, compared with the SPARCcenter 2000's maximum of 20 on dual XDBusses at 40 or 50 MHz and the SPARCserver 1000's maximum of 8 on a single XDBus.

Unlike the Sun SPARCcenter 2000 and SPARCserver 1000, each CS6400 is equipped with an external System Service Processor (SSP), a SPARCstation fitted with a JTAG interface to communicate with the CS6400 to configure its internal bus control card.

This included Starfire, the CS6400's successor then under development, which became the Sun Enterprise 10000.