Buffering control for accommodating variable data exchange rates

摘要

Digital data produced by a document scanner or other data source is sequentially stored in a memory. A remote data receiver generates requests for data causing communication of the data from the memory in the same sequence in which it was stored but at a rate substantially asynchronous with respect to the rate of scanner data production. Data is concurrently loaded into the memory and transferred from the memory to the receiver so that continuous data storage and transfer throughout the scan of a given image is possible. Data from the scanner is sequentially loaded into the memory in recycling sequences until there are no available memory storage sections. The scanner is then caused to stop scanning and to cease data production until transfer of data occurs from a memory storage section to the remote receiver. The scanner is thereafter enabled so as to resume with production of the next data following that which was last loaded into the memory. For a scanner, the data interruption and resumption is obtained by stopping and repositioning of the scanner bar relative to the document. Scanning is started or restarted when the data in the memory is inadequate to completely satisfy the current receive command.