Back at it again — working on another issue with the FIS. The twist this time? It passes all the tests…

With basic functionality restored, we need to re-run the floating point diagnostics test (BKEAB0) and address any remaining problems. Running The Diagnostics When running the diagnostics, we unsurprisingly receive an error printed to the console. ADR PS SP ANS1 ANS2 ----------------------------------- 004226 000050 000634 177520 017752 004226 000050 000634 177520

Last time we found and fixed a fault where the KE11-F was reading arguments from the wrong area of memory. That restored some basic functionality and allowed us to do some basic floating-point addition (1.0 + 1.0). Unfortunately, where we left off, the PDP-11 was still not passing the

Next up for repair is the PDP-11/40's Floating Instruction Set (FIS) board, also known as the KE11-F. The PDP 11/40 was unique in that the FIS and EIS (Extended Instruction Set) were optional. The FIS builds upon the functionality of the EIS, adding floating-point addition, subtraction,