System for combining and encoding first plurality of video signals to produce second plurality of signals and transmitting the signals via unshielded telephone cable to remote workstation

摘要

A type 286, 386, or 486 Personal Computer having a host controller comprising a standard VGA controller, a microprocessor, a receive and transmit unit, and an encoder is coupled via a ten line telephone cable to a remote VGA color display workstation having a base unit comprising a decoder, a RAMDAC, and microprocessor, and a receive and transmit unit. The encoder intelligently combines ten video signals (a pixel clock, six pixel signals, a video blanking interval (VBI) signal, and vertical and horizontal sync signals) and an I/O data transmit signal into four signals which are transmitted in a balanced fashion (requiring eight lines) to minimize signal noise so that shielding is unnecessary. An additional line is used to provide a ground reference to the remote workstation, and another line is used to provide an I/O data receive signal to the host controller microprocessor. The base unit decoder decodes the balanced signals to provide the I/O transmit signal to the base unit microprocessor, the vertical and horizontal sync signals to the remote workstation VGA monitor, and the VBI and pixel signals to the base unit RAMDAC. Remaining signals required by the base unit RAMDAC are provided by the base unit microprocessor.