As far as I understand it the speed of the port performing reads is goverend by the datastrobe/wait handshake cycle.Certainly if the remote device raises the datainterrupt then the port responds by aserting datasrobe it will time out if wait takes more than 10us to be asserted.In our case when we have data to send the '52 causes the interrupt,waits for datastrobe then sets wait when the data is on the port.
With an 8 read datstrobe goes low again,we set wait low and the cycle starts again.