移动通信的发展概述，从无到有，从1G到4G，到展望未来的发展趋势。-An overview of the development of mobile communications, from scratch, from 1G to 4G, to look to the future trend of development.

从头梳理传统功能手机的软硬件系统， 以此 为基础，分析当今智能手机的软硬件系统。-Scratch combing the traditional functions of mobile phone hardware and software systems as a basis for analysis of today' s smart phone software and hardware systems.

excel tutorial for beginners from scratch. its simple to understand and use for learning and commercial purpose

Building Hash table, linked list and quick sort scratch.-Building Hash table, linked list and quick sort scratch.