Abstract: A method and apparatus for configuring the address space of a computer is described. According to the present invention, a computer system has a full address space and includes at least one base unit, at least one expansion unit and a microprocessor core. The microprocessor core issues access addresses. The full address space includes a base address space and an expanded address space. The base address space is addressed by an M bit address and the expanded address space is addressed by an N bit address (N.gtoreq.M). Each base unit is mapped to an address within the base address space, and the base unit address is mirrored in the expanded address space. Each expansion unit is mapped to an address within the expanded address space. An address configuration circuit in the computer system includes an address space remapping circuit for selectively remapping or not remapping base units out of the base address space.

Abstract: A microcontroller with the capability of allowing a user to expand the capabilities of the controller such that the added functionality performs as if the controller were designed with that added functionality onboard. This capability is implemented by providing at the pinouts of the controller access to a special function register area onboard the controller, as well as certain internal control signals. Each peripheral controller which is desired to be interfaced with the microcontroller must have a special address decoding block added. By use of the present invention, a microcontroller can be customized to a user's specifications without the costs associated with a custom designed chip.