A4DF 18 EF 00 STY $00,Y ; UPDATE MICROCODE WORD

A4E2 18 08 INY ; POINTER FOR NEXT MICROCODE
A4E4 18 08 INY ;
I think that STY clear memory from 1400-15ff. It looks like it copies the value from 1400 and stores it[ $100 cycles word ] from 1400-15ff. 1400 looks like one of the injectors bpw so at reset should be cleared.

I think 16f0 needs more examination to figure what is going on at the hardware level. I am sure that 0003 sets some pin high or low on the ram chip, and some switching happens there. We have the microcode but no clue of the op codes it uses. Cracking the instruction set will open the door. Did you managed to define the memory range accessible to eside. I think that writing to the shared memory is a function of internal switching in the RAM chip. That extended ram chip might do more than we thought.