The invention relates to a microprocessor-based decoder board for an optical reader having in one embodiment a plurality of imaging modules that provide frames of image data having a plurality of formats. In one method for operating the decoder board of the invention, and a multiple imaging module reader comprising the decoder board, a frame of image data captured by a selected imaging module is decoded. The decoder board determines the format of the frame of image data from information about which of the plurality of imaging modules provided the frame of image data or from information about the frame of image data, activates as necessary a command to prepare the decoder board to decode the frame of image data according to the format provided by the imaging module, and performs the decoding.