Abstract: A method and computer system according to the disclosed invention comparing from right to left the ISDN device address embedded within an ISDN message with a pre-existing ISDN device number resident in the computer system. The computer system receives data containing the ISDN device address through the ISDN-type data communication device. Upon receiving the data, the computer system compares the ISDN device address with the resident ISDN device number contained in the computer system in a right to left matching scheme. If the ISDN device address and ISDN device number match using the right to left matching scheme, the computer system responds to the ISDN message through the ISDN-type data communication device.

Abstract: A computer system implements a standard modem without the use of a microcontroller. Instead, a digital signal processor is provided on an expansion card, but with direct links to the computer system itself. The code usually implemented in the microcontroller is instead implemented as a virtual modem controller to be called by the operating system of the computer itself. Further, this virtual modem controller includes a virtualized UART, that appears to the operating system software as a hardware UART, and the operating system driver software need not even have its input and output instructions replaced. Instead, debug registers are provided as breakpoints whenever an input/output instruction is executed to the I/O port range at which the UART would normally appear.

Abstract: An antenna system has a parabolic reflector mounted so that it points generally downwards and a primary aerial is located at the focus of that reflector. Waves from the primary aerial are reflected back by the parabolic reflector to a reflector plate through an aperture in which the primary aerial projects. Scanning in both elevation and azimuth is effected by movement of the reflector plate.