Abstract: A data communications system accommodates high transfer rates of non-isochronous data to and from a communications medium handling isochronous data. The system suitably includes an interface for transmitting non-isochronous data to and from a first system, such as a host system, and transmitting isochronous data to and from a second system, such as a WAN. The interface includes a clear-to-send (CTS) signal generated by the system receiving the non-isochronous data. If the CTS signal is asserted, the sending system continues to provide data to the receiving system. On the other hand, if the CTS signal is deactivated, the sending system withholds the non-isochronous data for the relevant channel until the CTS is reasserted. In an exemplary embodiment, the CTS signal is an out-of-band hardware-implemented signal, which tends to provide optimal simplicity and speed.

Abstract: A method and apparatus for transmission of time critical data over a modem link is disclosed. Time critical data is intercepted by a modem at its host input-output port. The intercepted time critical data is injected directly at the top of the queue of data intended for transmission over the modem link. The injection of time critical data takes place at the input to the modulator in the form of specially identified frames, preferably of short duration. Time critical data is thus sent on a priority basis bypassing error correction circuits or routines, and bypassing data compression. At a receiving modem, time critical data is recognized in the demodulator as specially identified frames or packets. Such time critical data is recovered and immediately sent to the host without passing through the error correction process and without decompression.