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title: Memory

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[ RNA, biological data storage [1] Memory is the ability to store, retain, and recall information and experiences as researched in cognitive science. Computer memory refers to physical devices used to store data and sequences of instructions (programs) on a temporary or permanent basis, typically distinguished as fast random-access memory and relatively slow data storage.

N-Bit Latches

N-Bit latches are arrays of one-bit latches or flip-flops typically as wide as a connected parallel data-bus. They may be used as a registers or scratchpad RAM inside a central processing unit.

RAM

Random access memory is a fast form of computer memory and refers to the idea that any piece of data can be stored and retrieved in a constant time, regardless of its physical location and whether or not it is related to the previous piece of data.

Static RAM

Static RAM (SRAM) is an array of latches, where each latch has a unique address, which connects the addressed latch to its data-bus, often used as CPU cache.

Dynamic RAM

Dynamic random access memory (DRAM) is a type of random access memory that stores each bit of data in a separate capacitor within an electronic circuit. Since capacitors leak charge, the information eventually fades unless the capacitor charge is refreshed periodically, which is the reason to call that memory dynamic. Since DRAM takes only one transistor and capacitor per bit, it is therefor used as cheap main memory part of recent computer data storage, despite its worse latency compared to SRAM.

[ DRAM write at a 4 by 4 array [7]

ROM

Read-only memory (ROM) is a class of storage programmed once and mainly used to distribute firmware. EPROMs have a small quartz window which admits UV light for erasure [8] . ROM or EPROM were often embedded inside a microcontroller in conjunction with some RAM. They were often used in dedicated chess computers.

[ National Semiconductor EPROMs 2764 and 2716 [9]

Since each data-bit stored in a ROM is a boolean function of its inputs or address, a ROM is also used to implement combinatorial logic.

Persistence

Auxiliary Storage

Beside the computer's random access main memory, auxiliary storage refer to mass storage like optical discs, and magnetic storage hard disk drives. Those devices are usually connected via a serial bus, and accessed via streams.

Compact Cassette as Auxiliary Storage in Intelligent Chess [10]

USB 3.0

Historical Data Storage

[ Plated wire memory from Wikipedia

[

Memory Hierarchy

ComputerMemoryHierarchy.svg

Memory Management

Todays processors utilize all the above types of memory from small and fast to large but slow within the concepts of virtual memory, paging, protection and various caches.

Virtual Memory

Page table actions.svg Virtual address space and physical address space relationship.svg
Physical address translation [12] Virtual and physical address space [13]

Paging

Page table Page replacement algorithm Paging Demand Paging Page fault Copy-on-write

TLB

Huge Pages

Note that what Windows calls "large pages," Linux and Unix call "huge pages" or "huge TLB pages (x86 and x86-64)

Memory Model

Shared Memory

Shared Memory:

False sharing from Wikipedia

Cache

Cache:

MSI protocol from Wikipedia MESI protocol from Wikipedia MOESI protocol from Wikipedia

assembly - The prefetch instruction - Stack Overflow Data Prefetch Support - GNU Project - Free Software Foundation (FSF) Software prefetching considered harmful by Linus Torvalds, LWN.net, May 19, 2011

Segmentation

Allocation

Manual memory management Memory leak Garbage collection

Memory Footprint

Beside their individual memory footprint, chess programs have to deal with huge memory areas of transposition table and possibly caches for endgame table- or bitbases and their relative huge random access latencies.

Miles Davis, Wayne Shorter, Herbie Hancock, Ron Carter, Tony Williams

Monika Malczak, Mateusz Gramburg, Paweł Zwierzyński-Pióro, Michał Szeligowski

Multiprocessing

Memory versus Search

See also

Publications

Computer Memory

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Memory part 1 Memory part 2: CPU caches Memory part 3: Virtual Memory Memory part 4: NUMA support Memory part 5: What programmers can do

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Cognition

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  • Adriaan de Groot (1966). Perception and Memory versus Thought: Some Old Ideas and Recent Findings. Problem Solving: Research, Method, and Theory (ed. B. Kleinmuntz), pp. 19-50. John Wiley, New York.

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Forum Posts

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External Links

Computer Memory

Gustavo Duarte's Blog

from Best Of by Gustavo Duarte:

Cognition

Neuroscience

Misc

References

  1. Data storage device from Wikipedia
  2. Selbsthaltefunktion from Wikidepia.de (German)
  3. Latch (electronics) from Wikipedia
  4. Flip-flop (electronics) from Wikipedia
  5. Bits by Lawrence J. Krakauer
  6. PDP-6 Circuit Instruction Manual, © 1966, Digital Equipment Corporation (pdf)
  7. Dynamic random access memory from Wikipedia
  8. How to program a 2716
  9. Category:EPROM 2716 - Wikimedia Commons
  10. Intelligent Chess from Chess Computer UK by Mike Watters
  11. 3D XPoint by Edmund Moshammer, CCC, August 02, 2015
  12. Page table from Wikipedia
  13. Virtual address from Wikipedia
  14. Buddy memory allocation from Wikipedia
  15. Cache-oblivious algorithm from Wikipedia
  16. Buddy memory allocation from Wikipedia
  17. DNA data storage breaks records : Nature News & Comment by Monya Baker, August 16, 2012
  18. DNA data storage breaks records by Terry McCracken, CCC, August 18, 2012
  19. April 01, 2018
  20. K-line (artificial intelligence) from Wikipedia
  21. Fernand Gobet (2007). Chunk hierarchies and retrieval structures: Comments on Saariluoma and Laine. Scandinavian Journal of Psychology, 42. pdf
  22. George Church, Yuan Gao, Sriram Kosuri (2012). Next-Generation Digital Information Storage in DNA. Science
  23. Hybrid Memory Cube from Wikipedia
  24. Intel Nehalem Core i3
  25. 3D XPoint from Wikipedia

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