操作系统5.输与输出InputOutput(IO).PDF

操作系统 5. 输⼊与输出 Input / Output (I/O) 任课教师：熊焰、⻩⽂超 I/O硬件原理 芯⽚ 软件接⼝ 电路 电源 硬件编程 硬件指令 ⻢达 调⽤函数 … 返回错误 电⼦⼯程师 程序员 Electrical 操作系统 Programers Engineers I/O硬件原理 I/O设备 • I/O设备的分类 • 块设备 (Block Devices) • 块⼤⼩固定，可寻址 • 硬盘、蓝光光盘、U盘 • 字符设备 (Character Devices) • 传输字符流，不可寻址 • 打印机，mice, rats…, 其它看起来不像磁盘的设备... SEC. 5.1 PRINCIPLES OF I/O HARDWARE 339 I/O硬件原理 I/O devices cover a huge range in speeds, which puts considerable pressure on the software to perform well over many orders of magnitude in data rates. Figure 5-1 shows the data rates of some common devices. Most of these devices tend to get faster as time goes on. I/O设备 Device Data rate Keyboard 10 bytes/sec Mouse 100 bytes/sec 56K modem 7 KB/sec Scanner at 300 dpi 1 MB/sec Digital camcorder 3.5 MB/sec 4x Blu-ray disc 18 MB/sec 802.11n Wireless 37.5 MB/sec USB 2.0 60 MB/sec FireWire 800 100 MB/sec Gigabit Ethernet 125 MB/sec