Abstract: An apparatus and methods for data exchange with microcomputing devices. In one embodiment, the invention consists of a microcomputing device having a plurality of instruction buses. The first bus is the primary instruction bus from which the device core receive application instructions. A secondary bus is the bus from which the device core receives data exchange instructions. Operative with the plural instruction buses is circuitry for receiving data exchange instructions on the secondary instruction bus and circuitry for selecting from which of the instruction buses the core fetches instructions on any given cycle. In addition to plural instruction buses, some instructions specific to data exchange have been added to the core's instruction set, allowing the device to perform data exchange instructions such as read and write with a single-word data exchange instruction. A method for summoning the core to perform a data exchange subroutine without the use of interrupts is provided.