Method and apparatus for processor emulation

An emulator for emulating the operation of data

• processing circuitry normally connected to and cooperable with a peripheral circuit, comprising:
• serial scanning circuitry connectable to the peripheral circuit for, when connected to the peripheral circuit, providing to and receiving from the peripheral circuit signals which would normally be provided and received by the data processing circuitry during normal cooperation between the data processing circuitry and the peripheral circuit, said serial scanning circuitry being connectable to an emulation controller for permitting serial data transfer between the emulation controller and the emulator;
• and
• control circuitry connected to said serial scanning circuitry and connectable to the emulation controller for, when connected to the emulation controller, effecting said providing and receiving of signals while serial data is being continuously transferred without interruption between the test controller and said serial scanning circuitry.