The SMMA flag indicates whether a
memory operation is already in
progress. If it is 0, no memory
operation is in progress. If it is 1,
a memory operation is in progress.
When the processor changes the state
of SMMA from 0 to 1, the memory starts
the operation. On completion of the
operation, the memory control logic
resets the flag. Obviously, this will
be done after the memory access time
is over. The MFC signal from memory
can be used to reset this flag.