Asynchronous memory devices utilize loopback circuitry to provide efficient and high speed \u201cflow-through\u201d of write data when conventional flow-through operations are not available. A main DC output voltage is regulated by a full bridge resonant switching converter with lossless switching of input power devices. In a preferred embodiment, the apparatus of the present invention includes a controller which receives binding purchase offers from prospective buyers. While the first connection is open, data traffic is conveyed between the mobile station and the subscriber unit via the second connection.