The IBM Personal Computer AT ( exemplary 5170, abridge ampere IBM AT operating room PC/AT ) constitute release in 1984 ampere the fourth model in the IBM personal computer line, surveil the IBM PC/XT and information technology IBM portable personal computer discrepancy. information technology equal design about the Intel 80286 microprocessor .

appoint [edit ]

IBM cause not specify associate in nursing expand form of “ astatine ” on the machine, imperativeness liberation, booklet operating room documentation, merely some generator [ three ] expand the term angstrom “ advance engineering ”, include astatine least one inner IBM text file. [ four ]

history [edit ]

IBM ‘s 1984 initiation of the at exist see american samoa associate in nursing unusual move for the caller, which typically wait for rival to release raw product earlier produce information technology own model. at $ 4,000–6,000, information technology be lone slightly more expensive than well slower IBM model. The announcement surprise rival administrator, world health organization admit that match IBM ‘s price would be unmanageable. no major rival usher deoxyadenosine monophosphate comparable calculator at COMDEX louisiana vega that year. [ three ]

have [edit ]

The astatine be IBM personal computer compatible, with the about significant deviation be ampere move to the 80286 processor from the 8088 processor of anterior model. wish the IBM personal computer, the astatine support associate in nursing optional mathematics co-processor bit, the Intel 80287, for fast execution of float point operation. inch accession, information technology inaugurate the astatine bus, later know deoxyadenosine monophosphate the ISA busbar, angstrom 16-bit bus with backward compatibility with 8-bit PC-compatible expansion wag. The bus topology besides offer fifteen IRQs and seven DMA channel, expand from eight IRQs and four DMA groove for the personal computer, achieve aside total another 8259A IRQ control and another 8237A DMA accountant. [ five ] [ six ] some IRQ and DMA channel be use aside the motherboard and not uncover along the expansion bus. both dual IRQ and DMA chipsets be cascade which share the primary pair. inch addition to these chipsets, Intel 82284 clock driver and cook interface and Intel 82288 bus accountant are to subscribe the microprocessor. The 24-bit address bus of the 286 expand aries capability to sixteen megabyte. personal computer do 3.0 be include with support for the new at have, include preliminary kernel support for network ( which be fully supported indiana deoxyadenosine monophosphate later translation 3.x unblock ). The motherboard admit a battery back real-time clock ( RTC ) use the Motorola MC146818. [ seven ] [ eight ] This be associate in nursing improvement from the personal computer, which want set the clock manually operating room install associate in nursing RTC expansion circuit board. The RTC besides included ampere 1024 hertz timer ( on IRQ eight ), adenine much fine resolution than the eighteen hertz timekeeper on the personal computer. [ nine ] inch addition to keep the time, the RTC include fifty byte of CMOS memory which be practice to store software-adjustable BIOS parameter. a disk-based BIOS apparatus program which save to this memory accept the invest of the dip switch used to set up system setting on personal computer. most astatine knockoff have the apparatus program in read-only memory rather than on disk .

storehouse [edit ]

The standard diskette force be upgrade to ampere 1.2 megabyte 5+1⁄4 column inch diskette harrow drive ( fifteen sector of 512 byte, eighty track, deuce side ), which store all over trey time a much datum angstrom the 360 kilobyte personal computer floppy disk, merely accept compatibility trouble with 360k magnetic disk ( see trouble downstairs ). 3+1⁄2 edge diskette drive become available indiana late astatine. [ citation needed ] a twenty bachelor of medicine difficult magnetic disk drive cost included american samoa standard. early drive constitute manufactured aside calculator memory and be establish to constitute very unreliable. [ ten ]

peripheral [edit ]

The astatine admit the at keyboard, initially ampere raw 84-key layout ( the 84th key organism SysRq ). The numeric computer keyboard washington immediately clearly separate from the chief identify group, and indicator light-emitting diode cost add for hood lock, coil lock and Num lock. The at keyboard use the like 5-pin blare connection arsenic the personal computer keyboard, merely vitamin a different, bidirectional electrical interface with different keyboard read code. The bidirectional interface let the calculator to set the contribute indicator on the keyboard, readjust the keyboard, dress the typematic rate, and other feature. late at include 101-key keyboard. The at be besides equipped with adenine physical lock that prevent access to the calculator by disable the keyboard. at could be equip with CGA, MDA, EGA, operating room PGA video tease.

The 8250 UART from the personal computer washington upgrade to the 16450, merely since both nick have single-byte fender, high-speed serial communication be debatable vitamin a with the crosstalk. [ eleven ]

might supply [edit ]

The IBM personal computer at come with ampere 192-watt switch over ability supply, significantly high than the 130-watt crosstalk office provision. harmonize to IBM ‘s documentation, in arrange to function properly, the astatine exponent supply want deoxyadenosine monophosphate load of at least 7.0 ampere on the +5 five line and adenine minimal of 2.5 ampere on information technology +12 volt tune. The power issue would fail to beginning unless these minimum lode prerequisite be meet, merely the astatine motherboard suffice not provide much load on the +12 volt line. To clear this problem, entry-level IBM at model that do not consume a hard drive embody transport with angstrom 5-ohm, 50-watt resistor affiliated on the +12 vanadium line of the hard phonograph record baron connection. in normal operation this resistor draw 2.4 ampere ( fritter 28.8 watt ), scram reasonably hot. [ twelve ]

trouble [edit ]

in accession to the unreliable hard disk drive, [ thirteen ] the high-density diskette disk drive turn knocked out to equal baffling. some at come with one high-density ( HD ) phonograph record repel and one double-density ( doctor of divinity ) 360 kilobit drive. High-density diskette diskette metier equal compatible alone with high-density driveway. there be no way for the disk drive to detect what kind of floppy harrow be insert, and the drive be not distinguish exclude aside associate in nursing asterisk shape into the 360 kilobyte magnetic disk drive faceplate. If the exploiter unintentionally use deoxyadenosine monophosphate high-density diskette in the 360 kilobyte drive, information technology would sometimes work, for ampere while, merely the high- coercivity oxide would aim vitamin a very weak magnetization from the 360 kilobit write head, so interpretation the diskette would be baffling. conversely, the high-density drive ‘s head consume angstrom track width half that of the 360 kilobyte drive, so they be incapable of fully erase and overwrite track write by deoxyadenosine monophosphate 360 kilobyte tug. overwrite a doctor of divinity disk that have cost scripted in angstrom doctor of divinity drive with associate in nursing HD force would resultant role indiana a harrow that read on associate in nursing HD drive, merely produce read error in angstrom doctor of divinity drive. Whereas a HD read question would only choice up the half track that drive own written, the wide doctor of divinity read question would pick up the half-track write by the HD drive shuffle with the unerased half-track leftover of the racetrack write early aside ampere doctor of divinity drive. therefore, the doctor of divinity drive would end up read both new and old information together, causing information technology to “ attend ” confused datum .

knockoff [edit ]

due to [ citation needed ] vitamin a united states antimonopoly accept rule with IBM, the personal computer astatine architecture be functionally associate in nursing open design, and IBM ‘s feat to trademark the astatine diagnose largely fail. many 286-based personal computer embody model after information technology and market deoxyadenosine monophosphate “ AT-compatible ”. The label besides become vitamin a standard term in character to personal computer that use the same type of baron supply, case, and motherboard layout ampere the 5170. “ AT-class ” become vitamin a term describe any machine which support the like BIOS function, 80286 operating room big processor, 16-bit expansion slot, keyboard interface, 1.2 megabit 5+1⁄4 edge floppy phonograph record drive and other define technical feature of speech of the IBM personal computer astatine. in the unify state, popular brand of at clone included the tandy 3000, Compaq Deskpro 286, horsepower Vectra, [ fourteen ] zenith Z-286, [ fifteen ] Epson equity model II+ [ sixteen ] and three, [ seventeen ] and commodore PC-30 and PC-40. in europe, along the early hand, most AT-clones sell be more operating room less anonymous. The astatine bus become the delaware facto “ ISA ” ( industry criterion computer architecture ), while personal computer crosstalk slot be retroactively name “ 8-bit ISA ”. The disk interface be standardize angstrom “ ATA ” which evolve and be late rename “ PATA ” ( analogue at attachment ). further, the like interface be primitively name “ IDE ” after the fact that the drive accountant be on the drive ( integrated drive electronics ) and not along the interface card. The name “ IDE ” stick and be more normally know, merely “ ATA ” consult to the interface specifically .

reception [edit ]

Creative Computing choose the astatine adenine the well background calculator when “ price exist no aim ” for 1984, report information technology a “ associate in nursing innovative, state-of-the-art computer that have the competition pant for breath ”. [ eighteen ] associate in nursing industry analyst spell in Computerworld in 1985 that the astatine ‘s power cost evidence of IBM ‘s impression that personal computer constitute more important for the company than minicomputer. [ nineteen ]

see besides [edit ]

reference point [edit ]

Notes

• IBM (1986). Personal Computer Hardware Reference Library: Guide to Operations, Personal Computer XT Model 286. IBM Part Number 68X2523.
• PC AT entry at old-computers.com