Interprocessor Buffer, PDP-11 to Positive Bus

This document contains two Field Change Orders (FCOs) for the DA28-F Interprocessor Buffer, which interfaces PDP-11 systems to the Positive Bus. FCO DA28F-B0001 (September 1973) addresses seven issues, including signal errors, misconfigured switches, and synchronization problems, requiring the addition of M133 and M246 modules and specific wiring changes. FCO DA28F-B0002 (January 1974) addresses reliability issues with PDP-11/40 and PDP-11/45 CPUs through extensive rewiring and corrects documentation errors.