dtj v04-03 1992

This issue of the Digital Technical Journal (Volume 4, Number 3, Summer 1992) focuses on NVAX-microprocessor VAX Systems, highlighting Digital Equipment Corporation's achievements in developing high-performance VAX microprocessors and integrating them into various systems.

Key themes and articles within the document include:

1. The NVAX Microprocessor: Described as Digital's fastest VAX implementation and the world's fastest shipping CISC microprocessor at the time. It uses advanced CMOS-4 (0.75-micrometer) process technology and incorporates RISC-like techniques (e.g., pipelining, multi-level caching) to dramatically improve VAX performance. NVAX is positioned as both an upgrade path for existing VAX systems and a migration path to the new Alpha AXP systems.
2. Design and Verification of the NVAX CPU Chip: Several articles detail the complex design challenges of the NVAX CPU chip (1.3 million transistors) and the innovative methods and CAD tools employed. This included rigorous simulation-based verification using pseudorandom exercisers and implementation-specific tests, as well as the critical role of a "patchable control store" (PCS) for debugging and on-the-fly corrections, which significantly accelerated development and resulted in highly functional first-pass chips.
3. NVAX System Implementations: The journal presents how the NVAX chip was integrated into different VAX system families:
   • VAX 6000 Model 600 Processor: A mid-range multiprocessing system that uses the NVAX CPU and a custom NEXMI interface chip, focusing on compatibility and performance goals.
   • VAX 4000 Models 400, 500, and 600 Systems: Deskside low-end systems that achieved significant performance increases by leveraging NVAX capabilities, along with new high-performance memory and VLSI bus adapter chips.
   • VAX 4000 Model 100 and MicroVAX 3100 Model 90 Desktop Systems: These designs prioritized aggressive time-to-market goals by extensively reusing and adapting existing components and designs.
   • VAXstation 4000 Model 90: A workstation that adopted programmable technology for new logic and utilized a breadboard system for rapid hardware and software verification and debugging.
4. Error Handling in VAX 6000 Systems: An article describes a pragmatic approach to error handling, emphasizing a common, object-oriented code base for error routines across different VAX 6000 CPU models to simplify development and ensure system integrity, recovery, and data preservation in complex multiprocessor environments.

Overall, the document showcases Digital's successful strategy of combining advanced microprocessor design with robust CAD tools and comprehensive verification efforts. The NVAX project achieved exceptional performance, surpassed initial goals, and delivered high-quality systems on or ahead of schedule, demonstrating a high degree of engineering excellence and collaborative effort.