Tandem NonStop VLX

The Tandem NonStop VLX was a high-performance third-generation implementation of the company’s proprietary stack architecture. ECL gate-array processors, 32-bit internal data paths and a faster Dynabus increased transaction throughput while preserving Guardian and application compatibility.

VLX sections could be expanded online and linked through FOX II across a campus. The system accompanied Tandem’s introduction of NonStop SQL, extending its role in continuously available relational database processing.

Notable Features

• The approximately 12 MHz ECL processor used 32-bit data paths and delivered roughly 3 MIPS per processor.
• A revised Dynabus supplied up to 20MB per second on each duplicated path.
• FOX II extended fibre-linked NonStop clusters across distances of several kilometres.

Historical Significance

• VLX moved Tandem further into mainframe-scale transaction processing while maintaining upward compatibility.
• The generation coincided with NonStop SQL, an early fault-tolerant relational database designed for continuous operation.

Collector’s Notes

• VLX cabinets, processors and disk subsystems were frequently upgraded over long working lives.
• Because ECL logic produces substantial heat, power and cooling arrangements are significant parts of an authentic installation.

Specifications

Technical Information
Name	Tandem NonStop VLX
Manufacturer	Tandem Computers
Launched	Tuesday, April 1, 1986
Discontinued	Early 1990s
Country	United States
CPU	Tandem proprietary VLX processor
Units Sold
Power	Redundant, serviceable system power supplies; requirements depended on cabinet configuration
Fault Tolerance	Self-checking processors, process pairs, dual buses, mirrored storage and redundant controllers
Architecture	ECL implementation of the TNS stack architecture with 32-bit internal data paths
Networking	Expand, Ethernet and enterprise protocols including X.25 and SNA; FOX II clustering
Operating System	Guardian 90XF with NonStop SQL
Expansion / I/O	Dual 20MB/s Dynabus paths and FOX II fibre-optic system links
Keyboard	External operator console terminal keyboard
Storage	Mirrored V8/XL8-class disk subsystems and magnetic tape with redundant controllers
Sound	No general-purpose sound hardware
Graphics	Terminal-oriented text output; no integrated graphics subsystem
Display	External operator console terminal; no integrated display
ROM	Boot, diagnostic and processor microcode storage; capacity varied by generation and configuration
RAM	Up to approximately 16MB per processor; larger distributed system totals
CPU Speed	83.3 ns cycle, approximately 12 MHz and 3 MIPS per processor