Search results
Results from the WOW.Com Content Network
An example of the latter is found in the Commodore 64, which uses a form of memory mapping to cause RAM or I/O hardware to appear in the 0xD000–0xDFFF range. Port-mapped I/O often uses a special class of CPU instructions designed specifically for performing I/O, such as the in and out instructions found on microprocessors based on the x86 ...
In computer science, a memory map is a structure of data (which usually resides in memory itself) that indicates how memory is laid out. The term "memory map" has different meanings in different contexts. It is the fastest and most flexible cache organization that uses an associative memory. The associative memory stores both the address and ...
Memory-mapped I/O, an alternative to port I/O; a communication between CPU and peripheral device using the same instructions, and same bus, as between CPU and memory; Virtual memory, technique which gives an application program the impression that it has contiguous working memory, while in fact it is physically fragmented and may even overflow ...
Special function registers are in the upper area of addressable memory, from address 0x80 to 0xFF. This area of memory cannot be used for data or program storage, but is instead a series of memory-mapped ports and registers. All port input and output can therefore be performed by memory move operations on specified addresses in the SFR region.
While often effective, employing a lookup table may nevertheless result in a severe penalty if the computation that the LUT replaces is relatively simple. Memory retrieval time and the complexity of memory requirements can increase application operation time and system complexity relative to what would be required by straight formula computation.
In a system using segmentation, computer memory addresses consist of a segment id and an offset within the segment. [3] A hardware memory management unit (MMU) is responsible for translating the segment and offset into a physical address, and for performing checks to make sure the translation can be done and that the reference to that segment and offset is permitted.
Alignment concerns can affect areas much larger than a C structure when the purpose is the efficient mapping of that area through a hardware address translation mechanism (PCI remapping, operation of a MMU). For instance, on a 32-bit operating system, a 4 KiB (4096 bytes) page is not just an arbitrary 4 KiB chunk of data. Instead, it is usually ...
An iconic example of virtual-to-physical address translation is virtual memory, where different pages of virtual address space map either to page file or to main memory physical address space. It is possible that several numerically different virtual addresses all refer to one physical address and hence to the same physical byte of RAM.