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Address spaces are created by combining enough uniquely identified qualifiers to make an address unambiguous within the address space. For a person's physical address, the address space would be a combination of locations, such as a neighborhood, town, city, or country. Some elements of a data address space may be the same, but if any element ...
A modern computer operating system usually uses virtual memory to provide separate address spaces or separate regions of a single address space, called user space and kernel space. [ 1 ] [ a ] Primarily, this separation serves to provide memory protection and hardware protection from malicious or errant software behaviour.
For example, the Data General Nova minicomputer, and the Texas Instruments TMS9900 and National Semiconductor IMP-16 microcomputers used 16 bit words, and there are many old mainframe computers that use 36-bit word addressing (e.g., IBM 7090, with 15-bit word addresses, giving an address space of 2 15 36-bit words, approximately 128 kilobytes ...
If paging is enabled, the base address in a segment descriptor is an address in a linear paged address space divided into 4 KB pages, so when that is added to the offset in the segment, the resulting address is a linear address in that address space; in IA-32, that address is then masked to be no larger than 32 bits. The result may be looked up ...
In computing, a virtual address space (VAS) or address space is the set of ranges of virtual addresses that an operating system makes available to a process. [1] The range of virtual addresses usually starts at a low address and can extend to the highest address allowed by the computer's instruction set architecture and supported by the operating system's pointer size implementation, which can ...
Relationship between pages addressed by virtual addresses and the pages in physical memory, within a simple address space scheme. Physical memory can contain pages belonging to many processes. Pages can be held on disk if seldom used, or if physical memory is full. In the diagram above, some pages are not in physical memory. A page table is a ...
Devices that do not support memory addresses long enough to address the entire physical memory can still address the entire memory through the IOMMU, avoiding overheads associated with copying buffers to and from the peripheral's addressable memory space. For example, x86 computers can address more than 4 gigabytes of memory with the Physical ...
Each segment was placed at a specific location in memory by the software being executed and all instructions that operated on the data within those segments were performed relative to the start of that segment. This allowed a 16-bit address register, which would normally be able to access 64 KB of memory space, to access 1 MB of memory space.