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Memory Model (other)
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Memory model may refer to: Psychology *Atkinson–Shiffrin memory model *Baddeley's model of working memory * Memory-prediction model Computer science * Memory model (programming) describes how threads interact through memory ** Java memory model ** Consistency model * Memory model (addressing scheme), an addressing scheme for computer memory address space ** Flat memory model ** Paged memory model ** Segmented memory ** One of the x86 memory models In computing, the x86 memory models are a set of six different memory models of the x86 CPU operating in real mode which control how the segment registers are used and the default size of pointers. Memory segmentation Four registers are us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atkinson–Shiffrin Memory Model
The Atkinson–Shiffrin model (also known as the multi-store model or modal model) is a model of memory proposed in 1968 by Richard Atkinson and Richard Shiffrin. The model asserts that human memory has three separate components: # a '' sensory register'', where sensory information enters memory, # a '' short-term store'', also called ''working memory'' or ''short-term memory'', which receives and holds input from both the sensory register and the long-term store, and # a '' long-term store'', where information which has been rehearsed (explained below) in the short-term store is held indefinitely. Since its first publication this model has come under much scrutiny and has been criticized for various reasons (described below). But it is notable for the significant influence it had in stimulating memory research. Summary The model of memories is an explanation of how memory processes work. The three-part, multi-store model was first described by Atkinson and Shiffrin in 1968, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baddeley's Model Of Working Memory
Baddeley's model of working memory is a model of human memory proposed by Alan Baddeley and Graham Hitch in 1974, in an attempt to present a more accurate model of primary memory (often referred to as short-term memory). Working memory splits primary memory into multiple components, rather than considering it to be a single, unified construct. Baddeley and Hitch proposed their three-part working memory model as an alternative to the short-term store in Atkinson and Shiffrin's 'multi-store' memory model (1968). This model is later expanded upon by Baddeley and other co-workers to add a fourth component, and has become the dominant view in the field of working memory. However, alternative models are developing, providing a different perspective on the working memory system. The original model of Baddeley & Hitch was composed of three main components: the ''central executive'' which acts as a supervisory system and controls the flow of information from and to its ''slave systems' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Memory-prediction Model
The memory-prediction framework is a theory of brain function created by Jeff Hawkins and described in his 2004 book ''On Intelligence''. This theory concerns the role of the mammalian neocortex and its associations with the hippocampi and the thalamus in matching sensory inputs to stored memory patterns and how this process leads to predictions of what will happen in the future. Overview The theory is motivated by the observed similarities between the brain structures (especially neocortical tissue) that are used for a wide range of behaviours available to mammals. The theory posits that the remarkably uniform ''physical'' arrangement of cortical tissue reflects a single principle or algorithm which underlies all cortical information processing. The basic processing principle is hypothesized to be a feedback/recall loop which involves both cortical and extra-cortical participation (the latter from the thalamus and the hippocampi in particular). The basic theory: recogniti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Memory Model (programming)
In computing, a memory model describes the interactions of threads through memory and their shared use of the data. History and significance A memory model allows a compiler to perform many important optimizations. Compiler optimizations like loop fusion move statements in the program, which can influence the order of read and write operations of potentially shared variables. Changes in the ordering of reads and writes can cause race conditions. Without a memory model, a compiler may not apply such optimizations to multi-threaded programs at all, or it may apply optimizations that are incompatible with multi-threading, leading to bugs. Modern programming languages like Java therefore implement a memory model. The memory model specifies synchronization barriers that are established via special, well-defined synchronization operations such as acquiring a lock by entering a synchronized block or method. The memory model stipulates that changes to the values of shared variables o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Java Memory Model
The Java memory model describes how threads in the Java programming language interact through memory. Together with the description of single-threaded execution of code, the memory model provides the semantics of the Java programming language. The original Java memory model developed in 1995, was widely perceived as broken, preventing many runtime optimizations and not providing strong enough guarantees for code safety. It was updated through the Java Community Process, as Java Specification Request 133 (JSR-133), which took effect back in 2004, for Tiger (Java 5.0). Context The Java programming language and platform provide thread capabilities. Synchronization between threads is notoriously difficult for developers; this difficulty is compounded because Java applications can run on a wide range of processors and operating systems. To be able to draw conclusions about a program's behavior, Java's designers decided they had to clearly define possible behaviors of all Java ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Consistency Model
In computer science, a consistency model specifies a contract between the programmer and a system, wherein the system guarantees that if the programmer follows the rules for operations on memory, memory will be data consistency, consistent and the results of reading, writing, or updating memory will be predictable. Consistency models are used in Distributed computing, distributed systems like distributed shared memory systems or distributed data stores (such as filesystems, databases, optimistic replication systems or web caching). Consistency is different from coherence, which occurs in systems that are cache coherence, cached or cache-less, and is consistency of data with respect to all processors. Coherence deals with maintaining a global order in which writes to a single location or single variable are seen by all processors. Consistency deals with the ordering of operations to multiple locations with respect to all processors. High level languages, such as C++ and Java (progr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Memory Model (addressing Scheme)
In computing, a memory address is a reference to a specific memory location in memory used by both software and hardware. These addresses are fixed-length sequences of digits, typically displayed and handled as unsigned integers. This numerical representation is based on the features of CPU (such as the instruction pointer and incremental address registers). Programming language constructs often treat the memory like an array. Types Physical addresses A digital computer's main memory consists of many memory locations, each identified by a unique physical address (a specific code). The CPU or other devices can use these codes to access the corresponding memory locations. Generally, only system software (such as the BIOS, operating systems, and specialized utility programs like memory testers) directly addresses physical memory using machine code instructions or processor registers. These instructions tell the CPU to interact with a hardware component called the memory contro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flat Memory Model
Flat memory model or linear memory model refers to a memory addressing paradigm in which "memory appears to the program as a single contiguous address space." The CPU can directly (and linearly) address all of the available memory locations without having to resort to any sort of bank switching, memory segmentation or paging schemes. Memory management and address translation can still be implemented ''on top of'' a flat memory model in order to facilitate the operating system's functionality, resource protection, multitasking or to increase the memory capacity beyond the limits imposed by the processor's physical address space, but the key feature of a flat memory model is that the entire memory space is linear, sequential and contiguous. In a simple controller, or in a ''single tasking'' embedded application, where memory management is not needed nor desirable, the flat memory model is the most appropriate, because it provides the simplest interface from the programmer's poin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paged Memory
In computer operating systems, memory paging is a memory management scheme that allows the physical memory used by a program to be non-contiguous. This also helps avoid the problem of memory fragmentation and requiring compaction to reduce fragmentation. Paging is often combined with the related technique of allocating and freeing ''page frames'' and storing pages on and retrieving them from secondary storage in order to allow the aggregate size of the address spaces to exceed the physical memory of the system. For historical reasons, this technique is sometimes referred to as ''swapping''. When combined with virtual memory, it is known as ''paged virtual memory''. In this scheme, the operating system retrieves data from secondary storage in blocks of the same size (pages). Paging is an important part of virtual memory implementations in modern operating systems, using secondary storage to let programs exceed the size of available physical memory. Hardware support is nece ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Segmented Memory
Memory segmentation is an operating system memory management technique of dividing a computer's primary memory into segments or sections. In a computer system using segmentation, a reference to a memory location includes a value that identifies a segment and an offset (memory location) within that segment. Segments or sections are also used in object files of compiled programs when they are linked together into a program image and when the image is loaded into memory. Segments usually correspond to natural divisions of a program such as individual routines or data tables so segmentation is generally more visible to the programmer than paging alone. Segments may be created for program modules, or for classes of memory usage such as code segments and data segments. Certain segments may be shared between programs. Segmentation was originally invented as a method by which system software could isolate software processes ( tasks) and data they are using. It was intended to incre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
