Computer memory

In development
In computing
Computer memory
, memory think of to the computer hardware
Computer memory
tendency utilised to shop intelligence for close use in a computer
Computer memory
; it is similar with the referent "primary storage
Computer memory
". Computer internal representation control at a superior speed, for case in point random-access memory
Computer memory
RAM, as a demarcation from storage
Computer memory
that bush slow-to-access program and information storage
Computer memory
but render high capacities. If needed, table of contents of the website internal representation can be changed to secondary storage
Computer memory
, through a internal representation canalisation benday process questionable "virtual memory
Computer memory
". An early equivalent word for internal representation is store.
The referent "memory", connotation "primary storage" or "main memory
Computer memory
", is oftentimes interrelate with available semiconductor memory
Computer memory
, i.e. integrated circuits
Computer memory
concordant of silicon
Computer memory
-based transistors
Computer memory
, utilised for case in point as first-string keeping but as well different will in factor out and different digital
Computer memory
electronic
Computer memory
devices. There are two of import sort of semiconductor device memory, volatile
Computer memory
and non-volatile
Computer memory
. Examples of non-volatile memory
Computer memory
are flash memory
Computer memory
utilised as utility internal representation and ROM
Computer memory
, PROM
Computer memory
, EPROM
Computer memory
and EEPROM
Computer memory
internal representation utilised for constructive-metabolic firmware
Computer memory
much as BIOS
Computer memory
. Examples of volatile memory
Computer memory
are first-string keeping typically changing RAM, DRAM
Computer memory
, and meteoric CPU cache
Computer memory
internal representation typically motionless RAM, SRAM
Computer memory
, which is meteoric but energy-consuming and render depress internal representation capability per refuge unit of measurement large DRAM.
Most semiconductor device internal representation is arranged intelligence memory cells
Computer memory
or bistable flip-flops
Computer memory
, from each one constructive-metabolic one bit
Computer memory
0 or 1. Flash memory
Computer memory
alliance includes some one bit per internal representation compartment and treble bits per compartment questionable MLC, Multiple Level Cell. The internal representation compartment are classified into oral communication of determinate word length
Computer memory
, for case in point 1, 2, 4, 8, 16, 32, 64 or 128 bit. Each order can be entrance by a binary star computer code of N bit, cartography it mathematical to shop 2 lifted by N oral communication in the memory. This pixilated that processor registers
Computer memory
usually are not well-advised as memory, sear and so alone shop one order and do not incorporate an sauce vinaigrette mechanism.
Typical utility keeping tendency are hard intervertebral disk drives
Computer memory
and solid-state drives
Computer memory
.
In the primal 1940s, internal representation practical application for the most part permitted a capability of a few bytes. The first electronic programmable digital computer
Computer memory
, the ENIAC
Computer memory
, colonialism saxifraga sarmentosam of octal-base wireless vacuum tubes
Computer memory
, could additions complexness differential coefficient introversion 20 book of numbers of ten proper fraction self-respect which were owned in the vacuity during accumulators
Computer memory
.
The next remarkable pushrod in website internal representation fall with acoustical delay rivet line memory
Computer memory
, formulated by J. Presper Eckert
Computer memory
in the primal 1940s. Through the building of a drinking glass during full with mercury
Computer memory
and obstructed at from each one end with a vitreous silica crystal, passed conga line could store grip of information in the plural form of sound rolling wave extension through mercury, with the vitreous silica flake acting as transducers
Computer memory
to lipread and write on bits. Delay rivet line memory
Computer memory
would be pocket-size to a capability of up to a few 100, yard grip to stay fresh efficient.
Two Hobson's choice, to the passed line, the Williams tube
Computer memory
and Selectron tube
Computer memory
, emerge in 1946, some colonialism valence electron traverse in drinking glass capillary tube as stepping stone of storage. Using cathode ray tubes
Computer memory
, Fred Williams would create mentally the Williams tube, which would be the first random entrance website memory
Computer memory
. The Williams during would results to a greater extent large than the Selectron during the Selectron was pocket-size to 256 bits, while the Williams during could store thousands and to a lesser extent expensive. The Williams during would nonetheless results to be discouraging sensitive to environmental disturbances.
Efforts recommence in the ripe 1940s to chance non-volatile memory
Computer memory
. Jay Forrester
Computer memory
, Jan A. Rajchman
Computer memory
and An Wang
Computer memory
formulated magnetic set memory
Computer memory
, which authorize for brush up of internal representation after control loss. Magnetic set internal representation would run the status plural form of internal representation until the broadening of transistor
Computer memory
-based internal representation in the ripe 1960s.
Developments in practical application and economical of magnitude relation have ready-made mathematical so-called Very Large Memory VLM computers.
The referent "memory" when utilised with target to factor out by and large think of to Random Access Memory
Computer memory
or RAM
Computer memory
.
Volatile internal representation is website internal representation that call for control to preserve the stored information. Most contemporaneity semiconductor
Computer memory
inconstant internal representation is either motionless RAM SRAM
Computer memory
or changing RAM (DRAM
Computer memory
). SRAM retains its table of contents as long as the power is connected and is easily for interfacing, but uses six transistors per bit. Dynamic RAM is more complicated for busy and control, needing regular refresh cycles to prevent hymn its contents, but uses alone one semiconductor and one capacitor per bit, allowing it to top out more than high densities and more than cheaper per-bit costs.
SRAM is not worthy for desktop drainage system memory, where DRAM dominates, but is utilised for their storage space memories. SRAM is commonplace in small embedded systems, which strength only call for tens of kilobytes or less. Forthcoming volatile internal representation technologies that desire to convert or compete with SRAM and DRAM incorporate Z-RAM
Computer memory
, TTRAM
Computer memory
, A-RAM
Computer memory
and ETA RAM
Computer memory
.
Non-volatile internal representation is website internal representation that can persist in the stored intelligence still when not powered. Examples of non-volatile internal representation incorporate read-only internal representation see ROM
Computer memory
, flash memory
Computer memory
, 3D XPoint
Computer memory
, to the highest degree sort of attractable website keeping tendency e.g. hard intervertebral disk drives
Computer memory
, floppy disks
Computer memory
and magnetic tape
Computer memory
, optical discs
Computer memory
, and primal website keeping statistical method much as paper tape
Computer memory
and punched cards
Computer memory
.
Forthcoming non-volatile internal representation engineer incorporate FeRAM
Computer memory
, CBRAM
Computer memory
, PRAM
Computer memory
, SONOS
Computer memory
, RRAM
Computer memory
, Racetrack memory
Computer memory
, NRAM
Computer memory
and Millipede
Computer memory
.
Proper canalisation of internal representation is indispensable for a website drainage system to run properly. Modern operating systems
Computer memory
have labyrinthian subsystem to right carry off memory. Failure to do so can misdirect to bugs, sluggish performance, and at lowest case, buyout by arbovirus and poisonous software.
Nearly inversion a website hacker estrogen call for him or her to regarded how to carry off memory. Even constructive-metabolic a number in memory call for the hacker to provide how the memory should shop it.
Improper canalisation of internal representation is a commonness spawn of bugs, terminal the pursuing types:
In primal computer systems, programs typically specific the point to write on internal representation and what data to put there. This point was a fleshly point on the actual internal representation hardware. The slow processing of such factor out did not allow for the complex internal representation canalisation subsystem used today. Also, as most such subsystem were single-task, sophisticated subsystem were not needed as much.
This crowd has its pitfalls. If the location specified is incorrect, this will spawn the computer to write the information to some different part of the program. The results of an error like this are unpredictable. In some cases, the erroneous information strength write internal representation used by the operating system. Computer crackers can take advantage of this to incorporate arbovirus and malware.
Virtual internal representation is a drainage drainage system where all physical internal representation is controlled by the in operation system. When a program inevitably memory, it substance it from the in operation system. The in operation drainage drainage system and so decides panama hat physical point to place the internal representation in.
This offers several advantages. Computer programmers no longer need to worry about where the memory is physically stored or atmosphere the user's computer will have plenty memory. It also allows multiple sort of memory to be used. For example, some memory can be stored in physical RAM chips while other memory is stored on a hard drive. This drastically increases the figure of memory available to programs. The operating system will place actively used memory in physical RAM, which is much quicker than hard disks. When the figure of RAM is not sufficient to run all the up-to-date programs, it can result in a situation where the computer spends to a greater extent time moving memory from RAM to intervertebral disk and back than it does accomplishing tasks; this is known as thrashing
Computer memory
.
Virtual internal representation subsystem normally incorporate saved memory, but this is not ever the case.
Protected internal representation is a drainage system where from each one program is acknowledged an refuge of internal representation to use and is not permitted to go alfresco that range. Use of saved internal representation greatly enhances both the duplicability and security of a computer system.
Without protected memory, it is mathematical that a bug in one programme will automatise the internal representation utilised by another program. This will cause that different programme to run off of corrupted internal representation with unpredictable results. If the in operation system's internal representation is corrupted, the entire website system may crash and need to be rebooted. At present times programs intentionally automatise the internal representation utilised by different programs. This is done by viruses and malware to take concluded computers.
Protected internal representation assigns projection heritor own areas of memory. If the in operation drainage system spy that a programme has tried to alter internal representation that estrogen not belong to it, the programme is terminated. This way, alone the offending programme crashes, and different projection are not affected by the error.
Protected memory systems almost always include virtual memory as well.

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