说明：  51单片机常用RAM初始化子程序库，包括片内RAM、片外RAM初始化、内部RAM数据复制程序、外部RAM数据复制程序、外部RAM数据复制到内部RAM程序等
(51 single-chip RAM used to initialize subroutine library, including chip RAM, chip RAM is initialized, the internal RAM data replication process, the external RAM data replication process, the external RAM to the internal RAM data replication procedures)