Abstract: A data compression controller for processing data between a host system and at least one device is disclosed. The data compression controller comprises a compression coprocessor for converting data between first format and second format at a determined controller ratio. The compression has two buffers for storing data of the first and second formats. When data is to be compressed, the coprocessor receives data directly from the host system into the first buffer. The coprocessor reads the buffered data and compresses the data for output to the external device through the second buffer. A coprocessor interface is coupled to the coprocessor for monitoring the buffers to determine the state of the buffers and the coprocessor; for example, if the such that the data to be compressed flows smoothly and consistently through the coprocessor. The input/output (I/O) controller is coupled to the coprocessor and the device for transferring data between the second buffer and the device.