Abstract: Methods and apparatus for creating microcode-implemented peripheral devices for a microcontroller core formed in a monolithic integrated circuit. The microcontroller core has a control store for storing microcode instructions; execution circuitry operable to execute microcode instructions from the control store; and means for loading a suite of one or more microcode-device modules defining an optional peripheral device, the optional peripheral device being implemented by microcode instructions executed by the execution circuitry in accordance with the definition provided by the microcode-device modules.

Abstract: The invention relates to a primary memory such as a dynamic random access memory, and a method and controller for controlling access to such a memory. The access control for the primary memory (60) is intimately associated with the microcode instructions of a processor (10) connected to the memory. The access control is integrated into the microcode program (22) of the processor, and each microcode instruction includes a control instruction used in controlling the operation of a memory controller (50). In the case of a DRAM, the DRAM controller (50) controls access to the DRAM (60) by executing, for each DRAM access, a sequence of DRAM control operations in response to a corresponding sequence of control instructions included in the microcode instructions of the processor.