The transmission of buffered data is coordinated between a storage medium and a host in response to a request from the host. One or more blocks of data are transferred from the storage medium to a buffer memory. One or more frames of data are transmitted from the buffer memory to the host, wherein the number of blocks ending in the frame is recorded in a blocks/frame register, and possibly also in a block count accumulator register. Buffer release pulses for releasing buffer space in memory are sent to the buffer memory, based on the number of blocks in the blocks/frame register, or the number of blocks accumulated in the block count accumulator register when a signal is received from the host. A pointer which points to the last block of data successfully transferred is updated in accordance with the buffer release pulses.