Abstract: Methods and apparatus for stepping-over and stepping-out of functions encountered during program execution on a target processor during debug operations are implemented within a combination of an emulator and a debug module. By having communication and storage devices available on-chip in the debug module, stepping and address compare details are conducted local to the processor at hardware speeds. The methods correctly determine necessary algorithmic steps to accommodate recursive and nested function calls without intervention by a combination of a host debug platform and a debug software application. This avoids the amount of time that would otherwise be necessary to cycle communications to the debug host level to accomplish the same processes. Override instructions for the target processor can be inserted and alternate memory locations jumped to under control of the same debug module, thereby using hardware resources efficiently.

Abstract: An eight-bit RISC based microcontroller includes an eight-bit register file having a dedicated arithmetic logic unit (ALU), in addition to a general purpose eight-bit ALU. The register file further includes means for combining a pair of registers to provide a logical sixteen-bit register for indirect addressing. The dedicated ALU is a sixteen-bit ALU which provides certain arithmetic functions for the register pair, thus alleviating the computational burdens that would otherwise be imposed on the general purpose eight-bit ALU. A further feature of the invention is the inclusion of a paging register which is combined with the contents of the logical sixteen-bit register to provide an even greater addressing range. Yet another feature of the eight-bit microcontroller of the present invention is the means for directly reading and writing to any bit position within the register file with a single instruction.

Abstract: An eight-bit RISC based microcontroller includes an eight-bit register file having a dedicated arithmetic logic unit (ALU), in addition to a general purpose eight-bit ALU. The register file further includes means for combining a pair of registers to provide a logical sixteen-bit register for indirect addressing. The dedicated ALU is a sixteen-bit ALU which provides certain arithmetic functions for the register pair, thus alleviating the computational burdens that would otherwise be imposed on the general purpose eight-bit ALU. A further feature of the invention is the inclusion of a paging register which is combined with the contents of the logical sixteen-bit register to provide an even greater addressing range. Yet another feature of the eight-bit microcontroller of the present invention is the means for directly reading and writing to any bit position within the register file with a single instruction.