DEC HSC50-AA Digital Equipment Mass Storage Controller w/ Installation Manual

DEC HSC50-AA Digital Equipment Mass Storage Controller w/ Installation Manual

The Digital Equipment Corporation (DEC) HSC50-AA is an intelligent mass storage controller built for VAX computing environments, communicating over DEC's CI (Computer Interconnect) bus. The HSC50 served as the central hub managing multiple disk and tape storage subsystems — offloading I/O processing from the host VAX CPU and enabling high-throughput, shared storage across clustered VAX systems. This listing includes the complete floor-standing cabinet with a populated card cage, internal power components, a collection of DEC tape cartridges, and the original HSC Installation Manual.

Specifications & What's Included

• Manufacturer: Digital Equipment Corporation (DEC)
• Model: HSC50-AA
• Type: Intelligent Mass Storage Controller
• Bus Interface: CI (Computer Interconnect) bus — configured as CI Node 0
• Power: 120/208Y VAC, 3-Phase, 60 Hz, 18A per phase, 3W+N+G
• Dimensions: 36" W x 22" D x 42" H (floor-standing cabinet)
• Approximate Weight: 360 lbs
• Country of Manufacture: USA
• Card cage: populated with multiple circuit boards across labeled slots (A–Y configuration visible)
• Drive bays: 2 front-access bays (labeled 0 and 1)
• Front panel indicators: State, Power, Init, Fault, Online LEDs
• Includes: collection of DEC-labeled tape cartridges in plastic sleeves (approx. 12+)
• Includes: HSC Installation Manual, part number EK-HSCMN-IN-001, in original DEC binder

Applications

The DEC HSC series was introduced in the early-to-mid 1980s as DEC's answer to high-performance shared storage for VAX clusters running VMS. The HSC50 (and its higher-capacity sibling, the HSC70) connected to VAX hosts via the CI bus — a proprietary high-speed interconnect that allowed multiple VAX nodes in a VAXcluster to share the same pool of RA-series disks (RA60, RA81, RA82, RA90) and TA-series tape drives simultaneously. This architecture was a major selling point for enterprise customers in the mid-1980s through early 1990s, particularly in banking, insurance, government, and manufacturing, where continuous availability and shared storage access were critical. The HSC50 handled all disk scheduling, error correction, and data transfer independently, reducing load on the host processors. Today these systems are of significant interest to VAX/VMS collectors, retrocomputing enthusiasts, and institutions preserving DEC hardware history. This particular unit has a documented museum provenance — it was maintained as a display piece at a Credit Union — making it a well-preserved example of this era of enterprise computing.