计算机组织与结构课件全分单元Ch071章节幻灯片.ppt

* * * * * * * * * * * * * * * * William Stallings Computer Organization and Architecture6th Edition Chapter 7 Input/Output The Computer 外设 通信线路 I/O 主存 CPU Input/Output Problems Wide variety of peripherals Delivering different amounts of data At different speeds In different formats often slower than CPU and RAM Need I/O modules Page196 I/O Module(Two major functions) Interface to CPU and Memory Interface to one or more peripherals Page196 Generic Model of I/O Module Page197 控制/状态 /数据 §7.1 External Devices Human readable Screen, printer, keyboard Machine readable Monitoring and control Communication Modem Network Interface Card (NIC) Page197 External Device Block Diagram Page198 变换器 控制 状态 数据 Control bus I/O Module Typical I/O Data Rates Page203 鼠标 键盘 千兆位以太网 图形显示器 硬盘 以太网 图形显示 扫描仪 激光打印机 软盘 调制解调器 §7.2 I/O Module Function Control Timing 控制和定时 CPU Communication 处理器通信 Device Communication 设备通信 Data Buffering 数据缓冲 Error Detection 检错 Page201 I/O Steps(Read) CPU checks I/O module device status I/O module returns status If ready, CPU requests data transfer I/O module gets data from external device I/O module transfers data to CPU Page201 CPU—I/O module—external Device data data I/O Module Diagram Page204 控制信息 状态信息 Input Output Techniques Programmed I/O 编程I/O ※Interrupt-Driven I/O 中断驱动I/O ※Direct Memory Access (DMA) 直接存储器存取 Page204 §7.3 Programmed I/O CPU has direct control over I/O Sensing status 检查设备状态 Read/write commands 发送读/写命令 Transferring data 传送数据 CPU waits for I/O module to complete operation Wastes CPU time Page204 Programmed I/O – detail CPU requests I/O operation I/O module performs operation I/O module sets status bits CPU checks status bits periodically周期性地 I/O module does not inform CPU directly I/O module does not interrupt CPU Page205 I/O Commands CPU issues address Identifies module ( device if 1 per module) CPU issues command Control - telling module what to do Test - check status Rea