KEV11-A floating point
From Computer History Wiki
The KEV11-A is an optional chip for LSI-11 CPU which adds support for the PDP-11 Extended Instruction Set and also FIS floating point.
For the KEV11-A, one version is a 3015 23-003B5 (seen with the first set of LSI-11 chips), which is suitable for the M7270 quad card etch revisions E and F, and the M7264 dual card. Another version is reported to be the 23-091A5, suitable for the M7270 quad card, etch revisions C and D.