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Operating Systems. An integrated collection of utilities… …that manage the operations of the hardware and maintain information storage and retrieval OS contains the “rules” of machine operation… …based on the architecture of the processor (CISC (pentium, power-pc), RISC (alpha, sparc, 680x0).
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Operating Systems • An integrated collection of utilities… • …that manage the operations of the hardware and maintain information storage and retrieval • OS contains the “rules” of machine operation… • …based on the architecture of the processor(CISC (pentium, power-pc), RISC (alpha, sparc, 680x0)
Components (must be resident in memory): • Supervisor = monitor, controlling unit • Coordinates all activities of the OS • Activates utilities as needed for functionality • Utilities = collection of sub-programs • I/O handling, user interface, scheduling, interrupt handling, memory management, program loading/unloading, foreground/background control, compression, paging, status…
Tree structures • Multi-user operating system • (UNIX) • Single-user operating system • (DOS) • (Windows) GUI representation of a “network-aware” environment
Multi-user structure (UNIX) • User sees a subset of the file structure • Administrator must protect the system files • User must protect own files (file rights) _____________ / [root]___________________________________ | | | | | /bin /home /usr /etc /unix |--|--|--|--|--|--| |--|--|--| |---|-| |---|---| |---|---| cat vi who ls /a …/z /bin passwd |----------|-----------| /acmt0001 /andj0001 …/others…[home – “root” to user] | | /homepage /homepage index.html index.html
Single-user structure (DOS) • View only one logical drive at a time • Logical drive represents the root • System files are accessible to user C: \ [root of logical drive] | | -DOS | -FORMAT.COM | -XCOPY.EXE | -MYFILES | -MYDOC.DOC | AUTOEXEC.BAT | CONFIG.SYS | COMMAND.COM
GUI representation (Windows) • Combines DOS structure with a global view • Includes hardware and logical world Desktop [user centric view of the world] | -MyComputer [computer centric view] | | +A:\ [root of logical drive] (floppy) | | +C:\ [root of logical drive] | | -DOS | | -Windows | | +D:\ [root of logical drive] | | +E: \[root of logical drive] (CD-ROM) | | -[printers] | | -[control panel] | | -[web pages] |-Network Neighborhood [peers] |-recycle bin |-myBriefcase
UNIX file rights - chmod • Set rights for: ugo (user, group, others) • Set access: rwx (read, write, execute) • home directory by default = drwxr-xr-x • remove read/write/exec for group and otherschmod go-rwx • make sure web pages are visible in /homepage chmod go+rx homepage