CONTROLLING ACCESS TO A PRIMARY MEMORY

摘要

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. Preferably, the control instruction included in each microcode instruction only constitutes a part of the microcode instruction, and the remaining part of the microcode instruction is used by the processor for other purposes, such as determining address information for the DRAM and processing the data that is transferred between processor and DRAM.