315-5195: unclear when the M68K can read register data

[jotego]

It looks like signal W31 will enable register writting. But it is not clear when the register data can be read by the M68K. It looks like registers 1 and 0 can be read (and 0xd 0xe during test) but what triggers that read? Is it W31 paired with the CPU read signal?

[furrtek]

I believe that the M68K can't read anything from the 315-5195, it can only write to registers at startup. The direction signal for the M68K data pins seems to only be controlled by the r/w operation system, which means that only a MCU write operation would make the pins become outputs. I can't see any path that would allow the M68K itself to do that.
Only the MCU seems to have data read access (see "MCU READ" sheet).

(W31 was renamed to /REGS_SPACE).