theory UNIX chap 1-4 Flashcards
(13 cards)
UNIX chap 1(UNIX)
- C was developed in unix
- The idea is that the os can run on any type of machine
- the problem is that the first edition(multics) was too ambition in its design
- the resulting architecture was too slow, too much complex functionality, Due to its complexity, it was also very difficult to write programs for
MULTICS - no screens,there was a terminal, this was the keyboard and printer
UNIX chap 2(Linux)
FSF?
what components does all linux distributions have in common?
advantages of linux?
- linux is derived from unix(not another unix
- linux was built as a clean room posix implementation of unix, posix is the specification that unix operating systems have toto adhere to for some degree of unix compatibility
* free software foundation - component of the GNU was talking long to develop(kernal) (abstraction of the cpu of the machine) thats what made it so difficult to build
- Kernal- memory, cpu cycles, i/o interfaces
GNU-system software, utilities and programs
*** linux is free: **
-can freely access and read the source code of the linux os
-can modify the linux kernal and system source code
-can freely use and distribute the binary code of the linux os
* linux is compatible with:
-file systems of a number of os
-network layers
-binary file execution formats
* linux is flexible:
-appliance-TV recorder
-standalone-jukebox
-network-internet
-personal desktop-graphical desktop
-workstation-scientific computation
-high performance computing-high performance scientific computation
chap 1(UNIX)
- c was developed in unix
- the idea was that the OS can run on any machine
- the problem with multics is that it was too ambitous in its design.. it has too much complex functionality..the resulting architecture was too slow..Due to its complexity , it was difficult to run programs
*no screens, only terminal(which was the keyboard and printer
chap 2(LINUX)
POSIX?
FSF?
- Linux is a clean room posix implementation of UNIX
- Linux is derived from UNIX(it is not a another unix
- POSIX is the specification that unix OS have to adhere to for some degree of UNIX compatibility
*free software foundation
-the component of the GNU was taking too long to build(kernal)..its an abstraction of the cpu of the machine
what components do all linux distributions have?
what are the advantages of linux?
- kernal-memory, cpu cycles, i/o interfaces
- GNU - system software,utilities and programs
* linux is free:
* You can freely access and read the source code of the Linux operating system.
* You are free to modify the Linux kernel and system source code.
* You can freely use and distribute binary code of the Linux operating system.
* linux is compatible with:
-file systmes of a number of os
-network layers
-binary file execution formats
* linux is flexible:
-appliance- tv recorder
-standalone-jukebox
-network-internet
-personal desktop-graphical desktop
-workstation-scientific computation
-high performance computing-high performance scientific computation
primary architectural characteristics of OS
- multi tasking-more than one program available
- multi user-more than one user can operate the machine simultaneosly
- multi processing-more than one task can be executed simultaneously
- kernal-core of the os, represents cpu, main memory and i/o
- shell-outside vierw, seen by users and applications for interaction
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UNIX vs WINDOWS
similarities
* both of concepts of users and groups of users
* both support a fairly wide variety of file systems
*both support the same I/o ports and devices
*both share the concept of services
Differences
* unix is network centric
windows can operate without a network
* unix is print centric
windows can operate without the awareness of printing functionality
*unix has an option GUI
windows is not very functional without its GUI
*unix has file name case sensitvity
- The kernal is loaded into memory at boot time, once it is initialised, it provides an abstract machine via the shell, to outside world users and applications
- when this call is made, the kernal flips the process into kernal mode, when the system call returns,, it goes back into user mode
- interacts with hardware components, provides services to hardware interfaces
-controls machine i/o, file i/o ,memory mangement and device management
-interacts with user mode programs, especially when they make system calls
ACL
access control
user-permissions for the user that owns the resource
group-permissions for all the users in the group that owns the resource
other- permissions for the users that are not in the group and not the actual user
processes vs tasks
- A task is a series of instructions that a computer carries out
- a task is a program or a sequence of programs
*several tasks can be executed by the same process sequentially
*several process can execute the same task simultaneously
*a process executes tasks in an address space
*a process is an instance of a task or a sequence of tasks in an execution
monolithic kernal vs micro kernal
- all hardware support is statically linked into one huge binary file that functions as the kernal when loaded into memory
- this type of kernal has a small set of kernal functions: synchronisation mechanism, schedullijng mechanism and communication
