PDP-11/74 Multiprocessor System Evaluation

This document outlines a detailed plan for the evaluation of the PDP-11/74 Multiprocessor System by Systems Evaluation Engineering. The primary objective is to assess the impact of multiprocessor (MP) additions on the PDP-11/70 processor, treating the 11/74 as a complete hardware/software system. The evaluation will encompass both dual and quad CPU configurations, with a strong emphasis on fault tolerance.

Key areas of evaluation include:

• Product Description: The 11/74 is designed as an upward-compatible processor to the 11/70, featuring specific modifications for MP capability, a new multiport memory system (MKA11), and a large buffer Massbus adapter (RH70-C). It supports 2 to 4 11/74 processors and runs on a new Multi-processor Operating System, RSX-11M-PLUS.
• Compatibility: Verification that the 11/74 processor maintains upward compatibility with the 11/70, and that the MP changes do not negatively affect performance or software compatibility. This includes testing existing software utilities and operating systems (e.g., RSX-11M, RSTS/E, RT11) alongside the new RSX-11M-PLUS.
• Performance: Benchmarking the 11/74 CPU performance against the 11/70, measuring hardware throughput, and analyzing memory sharing and lockout effects, with assistance from the Systems Performance Analysis group.
• Integrity: Comprehensive testing of device diagnostics (XXDP, DEC/X11), electrical characteristics (DC/AC power supply margining and consumption, ground/subsystem/port isolation, bus switch immunities), and Unibus/Memory Bus electrical integrity (Time Domain Reflectometer, DC loading, timing/voltage margins, crosstalk measurements).
• Fault Tolerance & Reconfiguration: Evaluation of power fail recovery, system fault insertion/detection, on-line and off-line diagnostics, independent processor/peripheral operation, and both manual and software-driven system reconfiguration. This includes assessing operator requirements, troubleshooting capabilities, and the time required for reconfiguration.
• Human Factors: Assessment of operator skills, documentation (operator's guide), and the human engineering aspects of reconfiguration and overall system operability, including field service feasibility.
• Configuration: Verification of Unibus configuration rules and analysis of intra-box/cabinet physical arrangements for potential electrical or physical problems.

The evaluation commenced with a dual CPU 11/74 system in June/July 1979, with a subsequent upgrade to a quad CPU configuration. It explicitly excludes environmental, EMI/RFI, 230 VAC/50 HZ power, fault insertion for diagnostics, and static discharge susceptibility testing. The project is projected to cost $60,000 and require 248 man-days, with a final report expected by December 1979.