3 I/O system management (4)Device Independence(设备独立性)and virtual device(虚拟设备) o Device independence(设备独立性)： 即program.与具体的设备无关。 使program易于重定向，增加了可移植性。 o Virtual device 东香兰xlanchen@ustc,edu.cn http:/staff..u011740i:Operating System操作系统原理 March28,201910/73
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 I/O system management (4) Device Independence (设备独立性) and virtual device (虚拟设备) Device independence(设备独立性): 即program与具体的设备无关。 使program易于重定向，增加了可移植性。 Virtual device 陈香兰 xlanchen@ustc.edu.cn http://staff.ustc.edu.cn/~xlanchen (Computer Application Laboratory, CS, USTC @ Hefei Embedded System Laboratory, CS, USTC @ Suzhou) 0117401: Operating System 操作系统原理与设计 March 28, 2019 10 / 73
4 File management(文件管理) o A file is a collection of related information defined by its creator. Commonly,programs data A logical storage unit ●Activities File creation and deletion ②Directory(目录)creation and deletion Support of primitives for manipulating files and directories Mapping files onto secondary storage File backup()on stable (nonvolatile)storage media 口1⊙生年12月0C 陈适兰xlanchen@ustc.edu.cn http:/staf.u01174Oi:Operating System操作系统原理斐 March28,201911/73
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 File management(文件管理) A file is a collection of related information defined by its creator. ▶ Commonly, programs & data ▶ A logical storage unit Activities 1 File creation and deletion 2 Directory(目录) creation and deletion 3 Support of primitives for manipulating files and directories 4 Mapping files onto secondary storage 5 File backup(备份) on stable (nonvolatile) storage media 陈香兰 xlanchen@ustc.edu.cn http://staff.ustc.edu.cn/~xlanchen (Computer Application Laboratory, CS, USTC @ Hefei Embedded System Laboratory, CS, USTC @ Suzhou) 0117401: Operating System 操作系统原理与设计 March 28, 2019 11 / 73
4 File management(文件管理) GOAL:方便用户，提供安全性 (1)文件存贮空间的管理 ·例：文件系统根据文件长度自动分配连续或离散的扇区，并提 供”一句柄”表示该文件。 (2)Directory management(目录管理) 。使用户按名存取，提高速度。 (3)文件的读、写管理和存取控制（即保护） 口1⊙注，1,2月00 陈适兰xlanchen@ustc.edu.cn http:/staf.u01174O1:Operating System操作系统原理 March28,201912/73
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 File management(文件管理) GOAL: 方便用户，提供安全性 (1) 文件存贮空间的管理 例：文件系统根据文件长度自动分配连续或离散的扇区，并提 供“一句柄”表示该文件。 (2) Directory management(目录管理) 使用户按名存取，提高速度。 (3) 文件的读、写管理和存取控制（即保护） 陈香兰 xlanchen@ustc.edu.cn http://staff.ustc.edu.cn/~xlanchen (Computer Application Laboratory, CS, USTC @ Hefei Embedded System Laboratory, CS, USTC @ Suzhou) 0117401: Operating System 操作系统原理与设计 March 28, 2019 12 / 73
5 Secondary storage management(辅存管理) o Usually disks used to store data that does not fit in main memory or data that must be kept for a "long"period of time. Proper management is of central importance Entire speed of computer operation hinges on disk subsystem and its algorithms o Activities Free-space management Storage allocation Disk scheduling o Some storage need not be fast Tertiary storage includes optical storage,magnetic tape Still must be managed Varies between WORM(write-once,read-many-times)and RW(read-write) 陈话兰xlanchen@ustc.edu:cn http:/staff.u0117401.Operating System操作系统原理 March28,201913/73
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Secondary storage management(辅存管理) Usually disks used to store data that does not fit in main memory or data that must be kept for a “long” period of time. Proper management is of central importance ▶ Entire speed of computer operation hinges on disk subsystem and its algorithms Activities 1 Free-space management 2 Storage allocation 3 Disk scheduling Some storage need not be fast ▶ Tertiary storage includes optical storage, magnetic tape ▶ Still must be managed ▶ Varies between WORM (write-once, read-many-times) and RW (read- write) 陈香兰 xlanchen@ustc.edu.cn http://staff.ustc.edu.cn/~xlanchen (Computer Application Laboratory, CS, USTC @ Hefei Embedded System Laboratory, CS, USTC @ Suzhou) 0117401: Operating System 操作系统原理与设计 March 28, 2019 13 / 73
6 User Interface Command-interpreter system(命令解释系统) User Interface(用户接▣) (1)命令接口 。由一组"命令”集组成，分为联机和脱机用户接口 联机用户接口：由一组键盘操作命令及命令解释程序所组成 脱机（批处理用户接口）：用CL写作业说明书 2)程序接口 ● system call(系统调用)） ·高级语言的库函数，如C库 (3)图形接口 。如win的copy文件，采用"拖”来完成，生动，不需记忆 东香兰xlanchen@ustc,edu.cn http:/staff..u0117401:Operating System操作系统原理 March28,201914/73
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 User Interface & Command-interpreter system(命令解释系统) User Interface(用户接口) (1) 命令接口 由一组“命令”集组成，分为联机和脱机用户接口 ▶ 联机用户接口: 由一组键盘操作命令及命令解释程序所组成 ▶ 脱机（批处理用户接口）: 用JCL写作业说明书 (2) 程序接口 system call(系统调用 ) 高级语言的库函数，如C库 (3) 图形接口 如 win的copy文件，采用“拖”来完成，生动，不需记忆 陈香兰 xlanchen@ustc.edu.cn http://staff.ustc.edu.cn/~xlanchen (Computer Application Laboratory, CS, USTC @ Hefei Embedded System Laboratory, CS, USTC @ Suzhou) 0117401: Operating System 操作系统原理与设计 March 28, 2019 14 / 73