A multi-protocol communications adapter (MPCA) is used to interconnect a Local Area Network (such as a store computing system) to a communications highway. The MPCA includes a plurality of protocol controllers, each one of the controllers being operable for converting a data stream into a predetermined format. A programmable configuration register is provided for selecting one of the protocol controllers. A controlled interface is provided for gating the selected controller onto the communications highway. The MPCA is packaged as a card or module. It is coupled to a primary computer that controls the Local Area Network. The primary computer may effectuate a protocol change by changing the contents of the configuration register. Thus, the MPCA can be used with a pre-existing primary computer without significantly changing the architecture and/or programming of said computer.