SPI接口4M位高速存储芯片，带2*512缓存-SPI interface 4M-bit high-speed memory chips, with 2* 512 cache

C51的入门教程，一步一步教会您使用C51进行单片机的开发，很不错。-C51' s entry-tutorial, step by step for the church you are using C51 MCU development, is pretty good.