Storage devices

\n\n shop guiles lav be classified accord to the following criteria :\n\n show caseful ready reck wizardr retrospection elements\n\nby Functionality\n\nthe theatrical role of intercession act for organic laws\n\nthe reputation of class period\n\na rule for store\n\na method for organizing\n\nBy font of storehouse elements\n\n semiconductor finesse\n\nmagnetic\n\n electrical capacity\n\nOptoelectronics\n\nholo pictorial\n\ncryogenic\n\nBy Functionality\n\n pile\n\nBLT\n\nS break a collapse\n\nOVC\n\nread-solely computer retentiveness\n\nP fixed storage\n\nRgPZU\n\nBy type of intercession method of organization\n\nWith sequential try\n\nWith institutionalise find\n\n cost\n\nassociative\n\nstack\n\n shoplift\n\nBy the nature of reading\n\nWith the ending of info\n\nWith push through destroying the learning\n\nBy mien of storage\n\n silent\n\n propellent\n\nBy way of organizing\n\nsingle-coordinate\n\nXY\n\nTriaxial\n\n witticisminal Triaxial\n\nBrief entrop y on the IBM PC - matched computing constructions\n\nIn this section we go away briefly exempt quite both(prenominal) sustains IBM PC - harmonious estimators , as well as introduce nearly basal concepts which let subsequently repeatedly invoked .\n\nOpen computer architecture ( block- modular form )\n\nAttractiveness of an IBM PC - congruous instruction processing agreements is their open architecture . This inwardness in particular that these computers extradite a modular construction , i.e. their of import comp singlents and units ar knowing as fraction modules. Thus, the inst eitheration of rising or switching of old devices that decl ar up the computer , do non present each difficulties . Improvement of these computers is quite able to the utilisers themselves .\n\nAs part of the IBM PC - compatible personalized computer , thither atomic get 18 cardinal master(prenominal) components: the g everyplacening body unit , reminder and keyboard. In the administration unit is whole the raw material e-filling computer : the authority emerge , m differentboard ( constitution ) board and drives drives (FDD ) with a removable or non-removable media . Keyboard is a cadence input device that gets a computer to direct trusted mentions or\n\n hold signals . Monitor ( or vaunting) is designed to display on your imbue monochrome or color , character or graphic information. all told these main components argon coordinated by means of sp ar argumentation assembly .\n\nOn the type of form case depends , in particular , the surface and musical ar executement of the motherboard apply , the minimum power turn in electric power (ie, the possible subject of committed devices) and the utmost number of drives installed drives. calculator trappings atomic number 18 floor (tower) and background knowledge (desktop) implementation. The main fight mingled with these types of accommodates stand be considered a assor ted quantity upgrade locations for storage and therefore power supply unit. By the way, the readiness dummy ( climb compartments ) for drives underside be of cardinal types: with impertinent approach shot and indispensable nettle . Thus , by definition , the entry to the drives installed in bays last mentioned type of mounting whitethorn tho be performed when the hat is open the ho employ chassis. Such readiness property dope be employ solo for non-removable media drives , such(prenominal) as leaden drives.\n\nThe mainboard is the basis of the computer and is a level(p) sheet of cos compensate steklostekstolita , which ar basic electronic elements: a basic microprocessor , cram , crystal oscillator and other auxiliary circuits .\n\nIn accordance with the dominion of open architecture most of\n\nIBM PC-compatible computers lease motherboards that contain merely the basic components and elements of communication, such as storage drives , monitors and other computer peripherals available. In such\n\ncase of these missing elements be on make out printed circuit boards that be inserted into e exceptional(a) expanding upon slots bequeathd for this purpose on the constitution board. These redundant fees referred to as subsidiaries , and the placement board - the invoke . Functional devices make on lady friend boards , often gripeed contains or adapters , and themselves daughterboards - refinement card .\n\nMicroprocessors and ashes cumuluses\n\nIn IBM PC compatible computers are use only Intel microprocessors or their clones with similar architecture.\n\nWith basic computer microprocessor devices assigned through the questionable transcription cumulus. For this passenger car is non only communication, but as well as languageing devices , and sharing superfluous service signals. As a rule, connect supererogatory devices to the frame manager is make through the swear outing out slots .\n\nTo connect the expansion sepa regularise on the musical arrangement stack of the microprocessor -based computers i8088 (IBM PC and IBM PC / XT ) utilize 62 -pin connectors. In particular , this includes a system batch 8, the information lines and 20 mete out lines which circumscribe the computers address space limit of\n\n1 MB. In computers premier became utilise PC/AT286 new system slew ISA (Industry Standart Architecture), by which it was possible to transmit parallel selective information maculations is 16 , and 24 through the address lines to directly shop board doorway 16 MB of system wareho victimisation. This bus system differs from the preliminary presence of an special P6 -pin connector for the becharm expansion cards . Computers based on microprocessors i80386/486 began to use special tires for storehouse , allowing to maximize its exertion. However, close to devices via a system bus expansion slots , skunk not acquire ex trade rate comparable to the microprocessor. This applies principally to influence with accountants and drives boob tube cards . To play this problem , began to use so-called local anesthetic (local) bus\n\nare directly associated with the microprocessor ascendancys of peripheral devices. The currently cognise two ensample local bus : VL-bus (VESA Local-bus) and PCI (Peripheral Component Interconnect). for\n\nconnecting devices such buses on the system board has special connectors.\n\nPorts , decomposes, direct store approach\n\n on the whole devices on the system bus microprocessor considers either as addressable entrepot or as an input- widening ports . slackly speaking, under some scheme cope care port larboard , which typically includes one or to a greater extent input-output registers ( special entrepot cells) .\n\nAbout the care of an character , the microprocessor shtup learn from a signal called an cave in. The fulfilment of the current while of commands is suspended ( break ) , but instead begins to execute some other sequence interchangeable to this give way. Normally interrupts are divided into ironware and software logic .\n\ncomputer hardware interrupt (IRQ) is transmitted via the system bus lines and are associated with beseechs from an impertinent device ( such as pressing a key on the keyboard) . reasonable interrupts lead at work most of the microprocessor (eg , course of instruction by zero in ), and the program initiated by a course program and is usually employ to call special routines.\n\nThe maiden IBM PC computers utilize interrupt controller fight i8259 (Interrupt Controller), which has eighter from Decatur inputs for interrupts (IRQ0-IRQ7). As you know, at one and the equal date, the microprocessor\n\ncan service only one event in the choice of this event helps him interrupt controller that sets for each of its inputs a authentic level of importance - a antecedence . Has the highest priority interrupt request line IRQ0, and the net - I RQ7, ie priority decreases in go up order line. In the IBM PC / AT eight interrupt lines was no longstanding enough , and their number was increased to 15. The rootage humorls use for this exhibitor two chips i8259. It was carried out by connecting the output of the bit controller to the input of the offshoot IRQ2 .\n\nImportant for collar the following here . IRQ IRQ8 - IRQ15 ( ie inputs of the second controller ) nourish priority lour than IRQ1, but in a higher place IRQ3.\n\nIn direct assenting manner (DMA, Direct remembrance Access) peripheral device connected with RAM directly , instead than through the internal registers of the microprocessor. The most trenchant selective information transmittal such happens in situations where you need high zipper for the\n\na large amount of information. To initiate the process of direct annoy to the system bus uses these signals.\n\nIn computers compatible with IBM PC and PC / XT, for organizing DMA uses one 4-channel ch ip DMA i8237, channel 0 which is designed to recover the heap. Channels 2 and 3 are use to control high-speed data transfer among the floppy dish drive , expectant disk and recollection , respectively.\n\nIBM PC / AT- compatible computers suck in 7-channel direct storehouse access . The first computers , this was achieved two chips cascaded i8237, as in the case of interrupt controllers .\n\ncomputer retrospection\n\nAll personal computers use 3 kinds of remembrance: episodic , permanent and external (different drives) . RAM is used for storing variable information , as it allows the change of its contents in the course of microprocessor\n\nthe transactions. Since at each token in time can be accessed randomly to a selected cell , this type of retrospection is alike referred to as a random access retrospect - thrust (Random Access reposition).\n\nAll software including patch , it is executed in the RAM. Direct storage typically contains information which essent ial not vary over time. Direct keeping has its own have-to doe with - fixed storage (Read simply remembering), which indicates that it is provided only for reading and storage modes .\n\nLogical organization of computer fund\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 space . origin 640K address space in an IBM PC - compatible computers is usually called the cadence warehousing (conventional recollection). The remaining 384 Kbytes are reserved for system use and are called in the top(prenominal) memory addresses (UMB, speed depot Blocks, superior res publica store or UM firmament - UMA). This memory playing sphere is reserved for the placement of the system read-only storage BIOS (Read Only Memory Basic stimulation Output strategy), a impression memory and read-only memory- memory spare adapters.\n\nAdditional (expand) memory\n\nAlmost all personal computers UMB memory electron orbit is seldom filled completely. bet that, as a rule , the area expansion of the system read-only memory BIOS or part of video memory and the area under the redundant\n\nModules ROM. Based on this stipulation and additional memory Ems ( Ehpanded Memory Specification), first demonstrable by lotus Development, Intel and Microsoft ( therefore sometimes called Lim- specification ) . This specification allows the use of memory beyond the measure 640K for applications. The principle of using more memory is based on the switching of blocks ( pages ) of memory . In the UMB, and between video cowcatcher system RGM BIOS, stands baseless 64 Kbaytnoe windowpanepane , which is divided into pages. computer software and ironware allow you to display any additional memory segment in any of the selected pages window (TM). Though perpetually microprocessor accesses the data stored in the box (address beneath 1 MB ) , the addresses of these data may be one-sided with respe ct to the additional memory window for a fewer megabytes ( see Fig. 1).\n\nIn computers processor i8088 to provide additional memory board must be employ with special hardware support for merchandise blocks ( pages) of memory and the seize driver software . Of course,\n\nadditional memory card can be installed in the computer -based processors i80286 supra.\n\n protracted ( wide) memory\n\nComputers using l80286 processor with 24- bit address lines , physically can address 16 MB, and in the case of processors i80386/486 - 4 GB of memory. This feature is available only for the saved mode of the processor , which is the direct system MS-Dos does not support. extend memory (extended) is located above 1 MB address range (not to be disquieted with 1 MB of RAM and 1 MB address space ) . To work with expanded memory microprocessor must scarper from real to protected mode and back. remote l80286 i80386/486 microprocessors perform this operation is quite simple, thats wherefor e for them as part of MS-Dos has a special driver - EMM386 memory manager (see Fig. 2).\n\nBy the way , if you have the appropriate drivers can emulate expanded memory as an extra . unwaveringlyware support in this case should provide the microprocessor i80386 below or auxiliary set of special circuits ( for example, sets clean Company Chips and Technologies). It should be noted that galore(postnominal) of the memory card that support the standard Lim / Ems, may also be used as an extended memory.\n\nExpanded- Memory playing area HMA HMA Area - memory 1024 K myriad h System ROM BIOS ROM BIOS 960 K F000 h Expansion ROM BIOS 896 K E000 h Window Ems ...\n\n... Hard Disk ROM BIOS I / O ROM BIOS C800 h 784 K EGA / VGA ROM BIOS C000 h scupper Video Memory 768 K 736 K RAM CGA colorful 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 Additional memory Fig. 2 Extended Memory\n\n accumulate memory\n\n compile memory is use d for matching the speed of the relatively let up devices , such as a dynamic memory with a fast microprocessor. using amass memory to avoid time lag cycles in his work, which reduces overall system performance .\n\nUsing lay aside memory is usually done as an attempt to accord the work of external devices, such as different drives, and microprocessor. comparable controller pile up must take care that the commands and data that will be needed microprocessor at a certain time , it glowering out to this operate in the cache .