These are the addresses used in a source code. The variable names, constants, and instruction labels are the basic elements of a symbolic address space.

These are the addresses at the time of compilation. A compiler converts symbolic addresses into relative addresses

These addresses are generated by the loader when a program is loaded into the main memory

Frame – This pertains to a fixed-length block of main memory

Page – This refers to a fixed-length block of data that resides in the secondary memory. A page of data may temporarily be copied into a frame in the main memory

Long-term scheduling – This involves a long-term scheduler, also known as a job scheduler, that determines which programs are admitted to the system for processing. Thus, it controls the degree of multiprogramming.

A variable-length block of data that resides in the secondary memory. An entire segment may temporarily be copied into an available region of the main memory, or the segment may be divided into pages, which can be individually copied into the main memory

This occurs due to the continuous loading and removal of processes in the memory, wherein free memory spaces are broken down into smaller fragments.

This occurs when the allotted memory blocks are of varying sizes. This builds up due to the continuous removal of processes in the main memory.

This occurs when the allotted memory blocks are of fixed size, and specific processes need more space or less space than the size of the allotted memory block

Sharing: Any protection mechanism must have the flexibility to allow several processes to access the same portion of the main memory

Physical organization: The task of moving and organizing information flow between the main and the secondary memory should be a system responsibility

Logical organization: Most programs are organized into modules, some of which are unmodified, read-only or execute-only, and some of which contain data that are modifiable.

Main memory – This is a volatile memory that provides fast access at a relatively high cost. The main memory technically holds programs and data that are currently in use.

This is usually a non-volatile memory at a cheaper cost with slower access. A secondary memory of large capacity is a good storage of programs and data for a longer term.

Fixed Partitioning. The main memory is divided into a number of static partitions at system generation time, wherein a process may be loaded into a partition of equal or greater size

Dynamic Partitioning. The partitions are created dynamically, wherein each process is loaded into a partition of exactly the same size as the process.

Simple Paging. The memory is divided into a number of equally sized frames, while each process is divided into a number of equally sized pages of the same length as the frames.

Simple Segmentation. Each process is divided into a number of segments, wherein a process is loaded by adding all of its segments into dynamic partitions.

Virtual memory is an abstraction of the main memory, providing processes and the kernel with their own, almost infinite, private view of the main memory

This partitioning method is similar to simple paging, but does not necessarily load all of the pages of the process. This has no external fragmentation and encompass large virtual address space, that may lead to a higher degree of multiprogramming.

This partitioning method is similar to simple segmentation, but does not necessarily load all the segments of a process. This has no internal fragmentation and encompass a large virtual address space, that may also lead to a higher degree of multiprogramming.

Scheduling or process scheduling is the act of selecting a job or a task that is to be dispatched. In some operating systems, other units of work, such as the input/output (I/O) operations, may also be scheduled

Long-term scheduling – This involves a long-term scheduler, also known as a job scheduler, that determines which programs are admitted to the system for processing.