3)Introduction to Operating systems (os), general architecture and organization.
Definitions, main functions, role of the OS, types and characteristics of an OS.
An operating system is a program that manages the computer hardware.
It also provides a basis for application programs and acts as an intermediary between the computer user and computer hardware.
Introduction to os Organization
Operating Systems today generally consist of many distinct pieces or components. We can simplify our description of an OS by viewing it as many layers of related components. A generic OS layered diagram is pictured below. Note the component at the top of the diagram is the user, and the component at the bottom of the diagram is the physical hardware. Management (control) of all tasks in between these two physical components is the responsibility of the OS.
T
he
computer architecture of a computing system defines its attributes as
seen by the programs that are executed in that system, that is, the
conceptual structure and functional behavior of the machine hardware.
Then, the computer architect defines the functions to
be executed in the hardware and the protocol to
be used by the software in order to exploit such functions. Note that
the architecture has nothing to do with the organization of the data
flow, the logical design, the physical design, and the performance of
any particular implementation in the hardware.
Hence By Architecture we mean the order in which certain hardware Processes are carried out by the OS and has nothing to do with the logical software flow of the Computer.
Simple view
An
Operating System is the layer between the hardware and software, as
in
An
Operating System is responsible for the following functions: Device
management using device drivers, Process management using processes
and threads, Inter-process communication, Memory management, File
systems.
In addition, all operating systems come with a set of standard utilities. The utilities allow common tasks to be performed such as: being able to start and stop processes, being able to organise the set of available applications, organise files into sets such as directories, view files and sets of files, editfiles, rename, copy, deletefiles, communicate between processes.
4)Major Achievements of os: the Process; Memory Management; Information Protection and Security; Scheduling and Resource Management; System Structure.
A process is an instance of a computer program that is being executed. It contains the program code and its current activity. Depending on the operating system (OS), a process may be made up of multiple threads of execution that execute instructions concurrently.[1][2]
A computer program is a passive collection of instructions; a process is the actual execution of those instructions. Several processes may be associated with the same program; for example, opening up several instances of the same program often means more than one process is being executed.
Memory management is the act of managing computer memory. The essential requirement of memory management is to provide ways to dynamically allocate portions of memory to programs at their request, and freeing it for reuse when no longer needed. This is critical to the computer system.Several methods have been devised that increase the effectiveness of memory management. Virtual memory systems separate the memory addresses used by a process from actual physical addresses, allowing separation of processes and increasing the effectively available amount of RAM using paging or swapping to secondary storage. The quality of the virtual memory manager can have an extensive effect on overall system performance.
Information security means protecting information and information systems from unauthorized access, use, disclosure, disruption, modification, perusal, inspection, recording or destruction.[1]
The terms information security, computer security and information assurance are frequently used interchangeably. These fields are interrelated often and share the common goals of protecting the confidentiality, integrity and availability of information; however, there are some subtle differences between them.
Resource allocation may be decided by using computer programs applied to a specific domain to automatically and dynamically distribute resources to applicants. It may be considered as a specialized case of automatic scheduling.
This is especially common in electronic devices dedicated to routing and communication. For example, channel allocation in wireless communication may be decided by a base transceiver station using an appropriate algorithm.]
One class of resource allocation algorithms is the auction class, whereby applicants bid for the best resource(s) according to their balance of "money", as in a online auction business model (see also auction theory).In one paper on CPU time slice allocation[3] an auction algorithm is compared to proportional share scheduling.
The set of programs intended for the solution of tasks on the personal computer, is called as the software. Structure of the software of the personal computer call a program configuration.The software, it is possible to divide into three categories conditionally:system software (public program), carrying-out various support functions, for example creation of copies of used information, delivery of reference information about the computer, check of operability of devices of the computer, etc.the application software providing performance of necessary works on the personal computer: editing of text documents, creation of drawings or pictures, processing of information massifs, etc.tool ON (programming systems), providing development of new programs for the computer in a programming language.