Digital Storage Systems Interconnect
The Digital Storage Systems Interconnect (usually given as DSSI) is a mass storage bus from DEC. It can also be used to create loosely-coupled multi-processors by sharing a number of disk drives between two systems. Such shared drives are termed 'Integrated Storage Elements' (ISEs).
DSSI is a 8-bit wide parallel bus. It is an alternate physical layer in the Computer Interconnect system; the CI system had a 'native' physical layer before the creation of DSSI. The DSSI specification lists the main attributes of DSSI as: multi-drop linear bus electrical topology; 8-bit parallel; low-cost, single-ended signalling interface circuitry; DC coupling.
Description from the 'Digital's Storage System Interconnect' protocol specification document:
"The DSSI, supporting the needs of low-end and mid-range systems, is one in a family of high-performance computer-to-computer interconnects .. that combine a common host interface and port layer with an implementation-specific datalink and physical interconnect. CI-class interconnects provide the transmission services required by Digital's Systems Communication Architecture (SCA) - a four-tiered set of protocols and interfaces as shown [to the right]."
DSSI made it possible to build VAXclusters from MicroVAX and smaller VAX computers by adding CI-bus functionality to smaller VAX systems.
Contents
Family of DSSI Products
DSSI Controllers/Interfaces
- KFQSA QBUS DSSI Adapter
- KFMSA XMI Dual DSSI Adapter
- KFMSB XMI DSSI adapter
- KFESA EISA DSSI Adapter
- KFESB EISA DSSI Adapter
- KFPSA PCI DSSI Adapter
- KFE52 VAXft Multi-Function Interface
- KDXDA VAXft 810 DSSI Interface
- EDA640 MicroVAX 3300/3400 KA640 embedded DSSI Adapter (EDA)
- KFA40 DEC 4000 I/O Module
DSSI Hierarchical Storage Controllers (HSDs)
DSSI Disk Drives
DSSI Tape Drives
External Links
- DSSI - DSSI and related documents at Bitsavers
- Digital's Storage System Interconnect - protocol specification document
- MicroVAX Dual-Host Systems (EK-338AC-DH-003) - contains a clear description of how a DSSI can be used to create a loosely-couple multi-processor
- RF Series Integrated Storage Element User Guide (EK-RF72D-UG-008)
