Editing Digital Storage Systems Interconnect (section)

== Operating system support in VAX/OpenVMS ==

   DSSI SUPPORT IN [[OpenVMS]]:
    OpenVMS VAX V5.0-2:
      o  Single- and Dual-Host support with 2 EDA640s ([[MicroVAX]] 3300/3400
         series).
      o  Systems Communications Services (SCS) for the VMScluster is run
        over the Network Interconnect (NI) for MicroVAX 3300/3400.
    OpenVMS VAX V5.1:
      o  Standalone support for the KFQSA.
      o  Up to 6 ISEs on a single DSSI bus regardless of whether 1 or 2
         hosts systems are attached to the bus.
    OpenVMS VAX V5.1-1:
      o  Dual host support for KFQSAs (1 KFQSA per system).
    OpenVMS VAX V5.2:
      o  For 3300/3400 series, SCS communication over the DSSI.
      o  Multiple KFQSA's per system, but *not* multiple dual-hosted
         DSSI's per system (here, multiple means 2, since only 2 hosts
         are allowed on the DSSI bus).
      o  DSSI adapter must connect to another like adapter, e.g. EDA640
          to EDA640 or KFQSA to KFQSA.
      o  Up to 7 ISEs on a single DSSI bus when only 1 host system is
         attached to the bus.
    OpenVMS VAX V5.3:
     o  Mixed DSSI adapters, i.e. EDA640 to KFQSA.
     o  Mixed DSSI adapters, i.e. EDA640 to KFQSA.
      o  Double dual-host configurations, i.e. 2 DSSI buses between two
         CPUs. Each bus is terminated at its own pair of adapters.
    OpenVMS VAX V5.3-2:
      o  Support for VAX 4000. (The VAX 4000 has 2 SHACs and can support
         two KFQSAs on the bus, so it can have up to 4 DSSI buses).
    OpenVMS VAX V5.4-2:
      o  Support for the KFMSA, an XMI to DSSI adapter. The KFMSA may
         only be used to single-host a VAX 6000 model or dual-host 2 VAX
         6000 models together.
    OpenVMS VAX V5.4-3:
      o  Tri-host configurations supported.
    OpenVMS VAX V5.5-2:
      o  Quad-host configurations with VAX 6000, [[VAX 7000/10000]]
         series systems now supported.
         NOTE: KFQSAs do not support SCS communication over the DSSI bus,
                they MUST have a NI connection in order to run the cluster
                software.
    OpenVMS Alpha V1.5, OpenVMS VAX V6.0:
      o  Quad-host DSSI configurations with [[DEC 4000 AXP]] systems supported.
         DEC 4000 systems can be configured only as end nodes on a DSSI
         bus, therefore, quad-host configurations must include at least
         two VAX systems.
      o  KFQSA Q-bus to DSSI configurations supported.
         VAX processors that use the KFQSA adapter can be placed on the
         same DSSI bus as DEC 4000 processors.