Microcode Does Not Handle Invalid/Illegal Commands

This document outlines FCO RA9X-F005 for RA90 and RA92 disk drives. Previous microcode releases failed to properly handle invalid and illegal commands, potentially causing the drive to hang and requiring a power cycle. It also notes issues with the Head offset table causing soft positioner errors.

The solution is to install Revision V27 microcode, which resolves these command handling issues, improves reliability, and enhances error reporting. The document provides instructions on determining if an update is necessary via system, controller, or drive-level checks, followed by step-by-step rework instructions for applying the V27 microcode.