Quoting Rananim:
737AvEng,
AT computer is fed by RA#1 or both RA#1 and RA#2 depending on software update.There are diagrams in the AMM showing this.
I haven't been able to find this info yet. Can you reference the section? I've looked at the differences between the Smiths Autothrottle Computer (which is what the accident aircraft had installed by line number) and the integrated Collins autothrottle card (line numbers 1270, 1272, 1278 and on have the autothrottle computer integrated into the FCC - FCC A is used for autothrottle).
Could you possibly be seeing the difference in rad alt connection to the FCC's? The Honeywell FCC's are not dually fed (directly) rad alt. The Collins FCC's are. There is a Honeywell FCC software change that
prevents one radio altimeter failure from causing an FCC to default to the 8 degree bank angle limit during an LNAV takeoff. This was standard ops with the Collins FCC's from the get go.