CPU Error Messages and Windows NT Support

This document outlines FCO KN470-AA-0001, which mandates the replacement of B2040-AA CPU modules with B2040-AB modules for all AS2000 and AS2100 5/250 systems. The upgrade addresses specific CPU timeout and I/O error messages (21164 Timeout or Fail I/O_00 0048) encountered during system power or reset, which can disable secondary CPUs. Additionally, this replacement removes existing operating system restrictions, enabling support for Windows NT. The procedure includes a caution regarding ESD safety and requires an orderly system shutdown, the use of the SHOW FRU command for identification, and module replacement. Installation verification is performed using the SHOW FRU command again to ensure all CPUs are correctly identified as B2040-AB and that no further errors are logged.