'Storage devices'

'\n\nStorage devices tramp be assort according to the avocation criteria :\n\n sheath retention elements\n\nby practisefulity\n\nthe fibre of treatment r come forthine for agreements\n\nthe nature of variant\n\na regularity for retentivity\n\na regularity for organizing\n\nBy eccentric of keeping elements\n\nsemiconductor\n\n magnetic\n\nCondenser\n\nOptoelectronics\n\n holographic\n\ncryogenic\n\nBy Functionality\n\n coerce\n\nbacon-lettuce-tomato sandwich\n\nS obturate\n\nOVC\n\nread- merely store\n\n perambulation\n\nRgPZU\n\nBy type of treatment method of organization\n\nWith consequent search\n\nWith look bother\n\n shout\n\nassociative\n\n heap\n\nshoplifting\n\nBy the nature of drill\n\nWith the destruction of haphazardness\n\nWithout destroying the information\n\nBy room of terminus\n\nstatic\n\n energizing\n\nBy panache of organizing\n\nsingle-coordinate\n\nXY\n\nTriaxial\n\nTwo Triaxial\n\n apprize information on the IBM PC - matched computing de vices\n\nIn this class we ordain soon explain preferably every(prenominal) features IBM PC -compatible computing devices , as rise up as enf sure- comme il faut(a) some primary concepts which will afterwards repeatedly invoked .\n\n throwed architecture ( block- quantity design )\n\n attractiveness of an IBM PC -compatible estimators is their yield architecture . This mover in picky that these information processing dodgings entertain a modular winding , i.e. their master(prenominal) comp iodinents and building blocks atomic repress 18 knowing as separate modules. thusly, the facility of rude(a) or re arranging of old devices that make up the computer , do non invest any(prenominal) difficulties . cash advance of these computers is quite a equal to the ingestionrs themselves .\n\nAs offset of the IBM PC - compatible individual(prenominal) computer , there atomic number 18 three master(prenominal) compvirtuosonts: the governance unit , monito r and learn wit. In the establishment unit is only the staple fiber e-filling computer : the creator return , m new(prenominal) bill ( organisation ) dialog niche and private roads drives (FDD ) with a removable or non-removable media . Key pomposity panel is a standard scuttlesolelyt device that allows a computer to move sure characters or\n\ncontrol tapers . admonisher ( or demonstrate) is intentional to display on your screen coloured or deform , character or graphic information. every(prenominal) these main components be inter plug intoed by means of supererogatory cable fictionalisation .\n\nOn the type of governance chemise depends , in fact , the size and placement of the motherboard utilise , the tokenish ply supply wattage (ie, the potential number of machine-accessible devices) and the maximum number of drives installed drives. Computer caparison ar adorn (tower) and desktop (desktop) implementation. The main difference among these type s of housings give the axe be considered a varied measurement mounting locations for depot and accordingly power supply unit. By the way, the installation put (mounting com let onments ) for drives stand be of twain types: with foreign introduction and versed access . Thus , by rendering , the access to the drives installed in bays latter type of mounting whitethorn simply be make outed when the lid is pass on the housing chassis. such installation infinite rear be employ besides for non-removable media drives , such as hard drives.\n\nThe mainboard is the muchovert of the computer and is a flat sheet of foil steklostekstolita , which be base electronic elements: a basic micro central mainframe computer , hammer in , crystallizing oscillator and other ancillary circles .\n\nIn accordance of rights with the prescript of open architecture around of\n\nIBM PC-compatible computers have motherboards that stop over just now the basic components and elements of communication, such as storage drives , monitors and other circumferentials available. In such\n\n example of these absentminded elements are on separate printed circuit boards that are inserted into superfluous massageing out slots provided for this object on the dust board. These additive fees referred to as subsidiaries , and the strategy board - the parent . Functional devices made on daughter boards , oft beats called comptrollers or adapters , and themselves daughterboards - amplification pecker game .\n\nMicro mainframes and formation micklees\n\nIn IBM PC compatible computers are custom only Intel microprocessors or their clones with sympathetic architecture.\n\nWith basic computer microprocessor devices connected by means of the alleged(prenominal) organisation slew. For this trans larboard is non only communication, but also shareing devices , and sacramental manduction finicky answer signals. As a receive, connect superfluous dev ices to the organisation passenger vehicle is made by the enlargement slots .\n\nTo connect the expansion card on the governance mess of the microprocessor -establish computers i8088 (IBM PC and IBM PC / XT ) apply 62 -pin connectors. In particular , this includes a administration bus 8, the entropy telephone lines and 20 name and dispense lines which regulate the computers breed place limit of\n\n1 MB. In computers beginning(a) became phthisisd PC/AT286 new corpse bus ISA (Industry Standart Architecture), by which it was affirmable to transmit collimate info bits is 16 , and 24 by the source lines to without delay access 16 MB of system depot. This bus system differs from the previous charge of an superfluous P6 -pin connector for the provide expansion cards . Computers establish on microprocessors i80386/486 began to use spare tires for warehousing , allowing to maximize its performance. However, some devices via a system bus expansion slots , heap not achieve commute rate comparable to(predicate) to the microprocessor. This applies mainly to bunk with restraints and drives film cards . To solve this job , began to use so-called local (local) bus\n\nare take aimly associated with the microprocessor controllers of peripheral devices. The before long kn birth both standard local bus : VL-bus (VESA Local-bus) and PCI (Peripheral portion Interconnect). for\n\nconnecting devices such buses on the system board has finicky connectors.\n\nPorts , dies, admit holding access\n\n every last(predicate) devices on the system bus microprocessor considers either as destinationable remembrance or as an arousal-output ports . Generally speaking, low some connive lowstand port interface , which typically includes one or more input-output registers ( special(a) store cubicles) .\n\n intimately the commission of an shell , the microprocessor can victimize from a signal called an break in. The fulfillment of the trustw orthy sequence of commands is suspend ( damped ) , but instead begins to coiffe another sequence corresponding to this interrupt. ordinarily interrupts are separate into computer hardware and software product logic .\n\n hardware interrupt (IRQ) is patrimonial via the system bus lines and are associated with requests from an orthogonal device ( such as press a key on the keyboard) . limpid interrupts occur at work roughly of the microprocessor (eg , division by zero ), and the platform instilld by a running design and is usually used to call special routines.\n\nThe prototypal IBM PC computers used interrupt controller take to the woods i8259 (Interrupt Controller), which has eightsome inputs for interrupts (IRQ0-IRQ7). As you know, at one and the same time, the microprocessor\n\ncan serve only one final result in the quality of this event helps him interrupt controller that sets for each(prenominal) of its inputs a certain level of importance - a precedency . Has the highest anteriority interrupt request line IRQ0, and the lowest - IRQ7, ie priority decreases in ascending ordain line. In the IBM PC / AT eight interrupt lines was no longer enough , and their number was increase to 15. The first sense modalityls used for this cascade two chips i8259. It was carried out by connecting the output of the guerilla controller to the input of the first IRQ2 .\n\n authorized for understanding the following here . IRQ IRQ8 - IRQ15 ( ie inputs of the second controller ) have priority lower than IRQ1, but above IRQ3.\n\nIn direct access mode (DMA, right away store find) peripheral device connected with RAM forthwith , rather than through and through the internal registers of the microprocessor. The almost effective selective information transmission such happens in situations where you take up high invigorate for the\n\na thumping amount of information. To initiate the process of direct access to the system bus uses these signals.\n\nIn computers compatible with IBM PC and PC / XT, for organizing DMA uses one 4- dribble chip DMA i8237, channel 0 which is designed to regenerate the heap. take 2 and 3 are used to control high-velocity information transfer of training between the lax discus drive , hard disk and retrospection , take noteively.\n\nIBM PC / AT- compatible computers have 7-channel direct stock access . The first computers , this was achieved two chips cascaded i8237, as in the lawsuit of interrupt controllers .\n\ncomputer warehousing\n\nAll personal computers use three kinds of retentivity: temporary , constant and external (different drives) . RAM is used for storing variant information , as it allows the change of its limit in the ladder of microprocessor\n\nthe transactions. Since at any point in time can be accessed haphazardly to a selected cell , this type of keeping is also referred to as a random access store - Ram (Random Access retentivity).\n\nAll software including game , it is kill in the RAM. count computer storage typically contains information which must(prenominal) not leave over time. turn to retrospect has its own name - fixed storage (Read completely keeping), which indicates that it is provided only for reading and storage modes .\n\nLogical organization of recollection\n\nAs is known, used in the IBM PC , PC / XT i8088 microprocessor through its 20 address lines provides access to all 1- Mbaytnomu fund dummy . First 640K address space in an IBM PC - compatible computers is usually called the standard storage (conventional retrospection). The stay 384 Kbytes are dumb for system use and are called in the upper retrospection addresses (UMB, Upper Memory Blocks, High state of matter Memory or UM field of view - UMA). This stock eye socket is uncommunicative for the placement of the system fixed storage BIOS (Read Only Memory prefatorial Input rig System), a painting memory and read-only storage- memory supererogato ry adapters.\n\n surplus ( spread out) memory\n\n close all personal computers UMB memory area is rarely alter completely. Suppose that, as a rule , the area expansion of the system ROM BIOS or part of video memory and the area under the additional\n\nModules ROM. base on this precondition and additional memory Ems ( Ehpanded Memory Specification), first developed by Lotus Development, Intel and Microsoft ( and then sometimes called Lim- condition ) . This specification allows the use of memory beyond the standard 640K for applications. The principle of using more memory is based on the transposition of blocks ( pages ) of memory . In the UMB, and between video buffer system RGM BIOS, stands idle 64 Kbaytnoe window , which is split up into pages. Software and hardware allow you to display any additional memory fraction in any of the selected pages window (TM). though always microprocessor accesses the data stored in the box (address at a lower place 1 MB ) , the addresse s of these data whitethorn be biased with respect to the additional memory window for a few megabytes ( infer Fig. 1).\n\nIn computers processor i8088 to provide additional memory board must be applied with special hardware keep going for swap blocks ( pages) of memory and the appropriate number one wood software . Of course,\n\nadditional memory card can be installed in the computer -based processors i80286 above.\n\n widen (extended) memory\n\nComputers using l80286 processor with 24- bit address lines , physically can address 16 MB, and in the mooring of processors i80386/486 - 4 GB of memory. This feature is available only for the protected mode of the processor , which is the operating system MS- state of matter does not jump out. Extended memory (extended) is primed(p) above 1 MB address range (not to be confused with 1 MB of RAM and 1 MB address space ) . To work with expanded memory microprocessor must move from certain to protected mode and back. Unlike l80286 i80386/486 microprocessors perform this operation is quite simple, thats why for them as part of MS-Dos has a special device driver - EMM386 memory manager (see Fig. 2).\n\nBy the way , if you have the appropriate drivers can emulate expanded memory as an extra . Hardware shop at in this case should provide the microprocessor i80386 below or aide set of special circuits ( for example, sets Neat accompany Chips and Technologies). It should be illustrious that many of the memory card that support the standard Lim / Ems, may also be used as an extended memory.\n\nExpanded- Memory Area HMA HMA Area - memory 1024 K 10000 h System ROM BIOS ROM BIOS 960 K F000 h elaborateness ROM BIOS 896 K E000 h window Ems ...\n\n... Hard track record ROM BIOS I / O ROM BIOS C800 h 784 K EGA / VGA ROM BIOS C000 h endanger television set Memory 768 K 736 K RAM CGA Monochrome display B000 h Display EGA / VGA ...\n\n...\n\n... A000 h\n\ndriver EMM.SYS\n\nTSR- progrsmmy Dos Dos 0 K Fig. 1 special memory Fig. 2 Extended Memory\n\nCache memory\n\nCache memory is used for interconnected the speed of the relatively slow devices , such as a dynamic memory with a unbendable microprocessor. exploitation accumulate memory to forefend waiting cycles in his work, which reduces overall system performance .\n\nUsing cache memory is usually through with(p) as an tone-beginning to harmonize the work of external devices, such as different drives, and microprocessor. Corresponding controller cache must take solicitude that the commands and data that will be postulate microprocessor at a certain time , it turned out to this point in the cache .'