Pos/355 Operating Systems Paper
Operating systems
Joseph N. Cleveland Jr.
University of Phoenix
Introduction to Operating Systems
POS/355
John Vassar
June 26, 2013
Memory management is an important characteristic of an operating system. Main memory is divided into two parts one for resident programs, and the other for the program currently in use. The user part must be subdivided to accommodate multiple processes (Stallings, 2012). When a few processes are in the memory then much of the time all of the processes will have to wait for input /output and the processor will be idle. According to Stallings (2012),. The requirements that memory management is supposed to satisfy are Relocation, Protection, Sharing, Logical organization, and Physical …show more content…
organization
Relocation is when a program is swapped in and out of the main memory to maximize processor utilization by providing a large pool of ready process ready to be executed.
The operating systems job is managing the memory. The operating system is in charge of bringing this process into main memory (Stallings, 2012). However the processor must deal with references within the program. Branch instructions include an address to reference the order to be executed next. Data reference instructions include the address of the byte or word of data referenced. The processor hardware and operating system software must be able to translate the memory references found in the code of the program into actual physical memory addresses, reflecting the current location of the program in main memory. (Stallings, 2012).
Protection is the next requirement to be satisfied. Protection deals with security against unwanted interference by other processes. Programs from other process should not be able to access memory locations in a process for reading or writing Purposes without permission. The processor must be able to abort such instructions at the point of execution.
Sharing allows several processes to access the same portion of main memory (Stallings, 2012). When there are a number of processes executing the same program it is beneficial to allow each process to access the same copy of the program rather than have its own separate copy (Stallings, 2012,). The memory management system must therefore
permit prohibited access to shared areas of memory without compromising vital protection.
Logical Organization: Main memory in a computer system is organized as a linear, or one-dimensional, address space, consisting of a sequence of bytes or words (Stallings, 2012). This organization emulates the actual machines hardware however it does not communicate the way in which programs are typically constructed. Most programs are organized into modules, some containing data that can be modified. Unmodified modules are either execute only or read only.
Modules can be written and assembled independently, with all references from one module to another resolved by the system at run time (Stallings, 2012,).
With additional overhead, different degrees of protection (read only, and execute only) can be given to different modules (Stallings, 2012,)
It is possible to initiate mechanisms by which modules can be shared between processes.
Physical Organization: consists of two parts the main memory, and secondary memory. Main
Memory is volatile and Main memory does not provide permanent storage. Main memory has
fast access at relatively high cost. Secondary memory of large capacity can be provided for long-
term storage of programs and data, while a smaller main memory holds programs and data
currently in use(Stallings, 2012,) .
References: Stallings, W. (2012). Operating Systems: Internals and design principles (7th ed.) Retrieved from University of Phoenix eBook Collection database.
Joseph N. Cleveland Jr.
University of Phoenix
Introduction to Operating Systems
POS/355
John Vassar
June 26, 2013
Memory management is an important characteristic of an operating system. Main memory is divided into two parts one for resident programs, and the other for the program currently in use. The user part must be subdivided to accommodate multiple processes (Stallings, 2012). When a few processes are in the memory then much of the time all of the processes will have to wait for input /output and the processor will be idle. According to Stallings (2012),. The requirements that memory management is supposed to satisfy are Relocation, Protection, Sharing, Logical organization, and Physical …show more content…
organization
Relocation is when a program is swapped in and out of the main memory to maximize processor utilization by providing a large pool of ready process ready to be executed.
The operating systems job is managing the memory. The operating system is in charge of bringing this process into main memory (Stallings, 2012). However the processor must deal with references within the program. Branch instructions include an address to reference the order to be executed next. Data reference instructions include the address of the byte or word of data referenced. The processor hardware and operating system software must be able to translate the memory references found in the code of the program into actual physical memory addresses, reflecting the current location of the program in main memory. (Stallings, 2012).
Protection is the next requirement to be satisfied. Protection deals with security against unwanted interference by other processes. Programs from other process should not be able to access memory locations in a process for reading or writing Purposes without permission. The processor must be able to abort such instructions at the point of execution.
Sharing allows several processes to access the same portion of main memory (Stallings, 2012). When there are a number of processes executing the same program it is beneficial to allow each process to access the same copy of the program rather than have its own separate copy (Stallings, 2012,). The memory management system must therefore
permit prohibited access to shared areas of memory without compromising vital protection.
Logical Organization: Main memory in a computer system is organized as a linear, or one-dimensional, address space, consisting of a sequence of bytes or words (Stallings, 2012). This organization emulates the actual machines hardware however it does not communicate the way in which programs are typically constructed. Most programs are organized into modules, some containing data that can be modified. Unmodified modules are either execute only or read only.
Modules can be written and assembled independently, with all references from one module to another resolved by the system at run time (Stallings, 2012,).
With additional overhead, different degrees of protection (read only, and execute only) can be given to different modules (Stallings, 2012,)
It is possible to initiate mechanisms by which modules can be shared between processes.
Physical Organization: consists of two parts the main memory, and secondary memory. Main
Memory is volatile and Main memory does not provide permanent storage. Main memory has
fast access at relatively high cost. Secondary memory of large capacity can be provided for long-
term storage of programs and data, while a smaller main memory holds programs and data
currently in use(Stallings, 2012,) .
References: Stallings, W. (2012). Operating Systems: Internals and design principles (7th ed.) Retrieved from University of Phoenix eBook Collection database.