{HEAD ~ A hand shake type control circuit} for controlling {TAIL ~ a data transfer circuit} according to the status of a data transfer request signal 
for controlling
{ HEAD ~ A hand shake type control circuit } for controlling { TAIL ~ a data transfer circuit } according to the status of a data transfer request signal
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH