1. A multi-frequency transponder for communicating at a first frequency according to a first communication protocol and at a second frequency according to a second communication protocol, the second frequency being different from the first frequency, the transponder comprising: a first physical memory with a first memory structure optimized for storing a first set of data of the first communication protocol; a second physical memory with a second memory structure optimized for storing a second set of data, different from the first set of data, of the second communication protocol; and logic circuitry configured to access the first and second physical memories, the logic circuitry comprising a first control circuit configured to handle communications according to the first protocol, and a second control circuit configured to handle communications according to the second protocol, wherein the transponder further includes a mapping memory configured to store a logical memory map of at least one of the first and second physical memories, the logical memory map comprising mapping information for the logic circuitry to access data items in both the first and second physical memories.