The thesis uses PC's Direct Memory Access idea for reference to put forward direct access Single-clip Microcomputer's extension Read Access Memory concept. Then explains hardware and software realize for it in details. 借鉴PC机DMA思想提出单片机片外数据存储区直接存取概念,并详细阐述了PC机直接存取单片机内存的软硬件实现方法。