Need chip selects.
Control concept needs more detail - how differentiate between
register address, read/write, data,
and
start address, read/write, data
or
start address, more address, read/write, data, data, data, data?
Can be made to look like a FIFO. FIFO on the other hand, just catch all writes, read them all back, let the software determine if what went out is what was intended.
Or is that what you were thinking? Just capture everything as bytes, no interpration, and read it back? (Sorry Rob, it's kinda late here)
In which case, just need the chip selects.