FCO DEQNA-0002, Late collisions on packets undetected

This Field Change Order (FCO DEQNA-0002) addresses critical issues in DEQNA (M7504) Ethernet controllers, specifically undetected late collisions on received packets and undetected data corruptions due to transmit buffer RAM problems.

The FCO mandates replacing existing DEQNA-M (M7504-00) or DEQNA-SA (M7504-PA) modules with specific revision levels (K3 or higher for DEQNA-M, D1 or higher for DEQNA-SA) if they exhibit these symptoms. The rework procedure involves a safe system shutdown, disconnecting AC power, removing the old module, verifying jumper settings, and installing the new module. For target systems, the Station Address PROM can optionally be transferred from the old to the new module; if not, the host system's DECnet database or system configuration must be updated with the new Ethernet address. The document provides instructions for obtaining this new address from the console for µVAX II and PDP11 systems.

Installation is verified by power-up microdiagnostics (LEDs turning off), and the process concludes with documenting the changes in the LARS system and the Site Management Guide. The estimated installation time is 1.0 hour.