计算机专业英语(霍洪涛)课件Chapter 3.ppt

Chapter 2 Data Structure Review mount v. If you mount an object on something, you fix it there firmly. configure v. If you configure a piece of computer equipment, you set it up so that it is ready for use. Install v. If you install a piece of equipment, you put it somewhere so that it is ready to be used. * Review 扩充槽 主板 基本输入/输出系统 节能模式 插头插座 盛行很广的 利用 衡量标准 分层结构 * expansion slot system board/motherboard basic input/output system(BIOS) power saving mode plug socket prevailing take advantage of metric hierarchy Review Why we need cache? * Microprocessors are faster than main memory. Memory access time is increasingly the bottleneck in overall application performance. One way to overcome this problem is to insert a small high-speed buffer memory between the processor and main memory. Such a buffer is generally referred to as cache memory. Review Cache hierarchy * It is possible to implement multiple levels of cache memory. Some of these levels will be a part of the microprocessor(they are said to be on-chip), whereas other levels may be external to the chip. To distinguish between these caches, a level notation is used. The higher the level, the farther away the cache is from the CPU. Unit 1 Balanced Tree Data Structure Introduction(P40) Why do we need a balanced tree? When working with large sets of data, a relatively small portion of the data structure is maintained in primary storage(RAM), and additional data is read from secondary storage as needed. Unfortunately, most secondary storage is significantly slower than RAM. 在操作很多组数据的时候，有一小部分的数据结构存在RAM里，额外的数据在需要的时候从次存储器里面读取。很不幸的是，大部分的次存储器的速度都比RAM慢。 * Unit 1 Balanced Tree Data Structure Introduction(P40) Why do we need a balanced tree? Balanced trees are optimized for situations when part or entire tree must be maintained in secondary storage. Since disk accesses are expensive operations, a balanced tree tries to minimize the number of disk ac