M8108

This document is an Engineering Change Order Log from Digital Equipment Corporation, detailing various problems and corrections for the M8108 System Status Registers (KT11-C), used in PDP-11/45 and PDP-11/50 processors.

The log, spanning from April 1972 to May 1973, addresses a range of issues including:

• Circuit and Logic Errors: Such as wrong termination, race conditions, incorrect flip-flop settings, and issues with INHIBIT signals.
• Instruction Handling: Specifically, problems with the MTPI instruction writing to incorrect memory spaces.
• Address Errors: Occurring during console physical operations or due to illegal internal register access.
• Physical Board Discrepancies: Corrections to etched board layouts (cuts and jumpers) to match schematic revisions.
• Documentation Inaccuracies: Updates to reflect correct etch revisions in drawings.

Many corrections require immediate rework of existing M8108 modules across various etch revisions (e.g., "A" and "B" boards), while some are documentation-only changes or phase-ins for new production. The log also includes notes on dependencies with other modules (like KB11-A) and warnings about potential processor hangs.