METHODS AND CORES USING EXISTING PLD PROCESSORS TO EMULATE PROCESSORS HAVING DIFFERENT INSTRUCTION SETS AND BUS PROTOCOLS

Methods and cores using an existing processor implemented in a Programmable Logic Device (PLD) to emulate a target processor, where the existing and target processors support different instruction sets and conform to different bus interface protocols. A bus interface unit is coupled to an existing processor in a PLD. The bus interface unit is implemented using the programmable logic resources of the PLD, while the existing processor can be a dedicated processor or an existing “soft” processor. The bus interface unit acts as a peripheral device to translate bus transactions from the existing bus protocol (i.e., the bus protocol understood by the existing processor) to the target bus protocol. In addition, a stored emulation program emulates the target instruction set while executing instructions using the instruction set supported by the existing processor.