IBM Personal Computer AT: Difference between revisions

Latest revision as of 01:20, 23 December 2025

Template:Short description Template:Use mdy dates Template:Infobox information appliance

The IBM Personal Computer AT (model 5170, abbreviated as IBM AT or PC/AT) was released in 1984 as the fourth model in the IBM Personal Computer line, following the IBM PC XT and its IBM Portable PC variant. It was designed around the Intel 80286 microprocessor.

Name

IBM did not specify an expanded form of AT on the machine, press releases, brochures or documentation, but some sources^[1] expand the term as Advanced Technology, including at least one internal IBM document.^[2]

History

IBM's 1984 introduction of the AT was seen as an unusual move for the company, which typically waited for competitors to release new products before producing its own models. At $4,000–6,000, it was only slightly more expensive than considerably slower IBM models. The announcement surprised rival executives, who admitted that matching IBM's prices would be difficult. No major competitor showed a comparable computer at COMDEX Las Vegas that year.^[1]

In April 1986 IBM revised the AT, increasing the speed of its Intel 80286 CPU from 6 to 8 MHz.^[3]

File:IBM 5170 with Floor Standing Enclosure.jpg

IBM 5170 with Floor Standing Enclosure^[4] and compatible non-IBM display

Features

The AT is IBM PC compatible, with the most significant difference being a move to the 80286 processor from the 8088 processor of prior models. Like the IBM PC, the AT supported an optional math co-processor chip, the Intel 80287, for faster execution of floating point operations.

In addition, it introduced the AT bus, later known as the ISA bus, a 16-bit bus with backward compatibility with 8-bit PC-compatible expansion cards. The bus also offered fifteen IRQs and seven DMA channels, expanded from eight IRQs and four DMA channels for the PC, achieved by adding another 8259A IRQ controller and another 8237A DMA controller.^[5]^[6] Some IRQ and DMA channels are used by the motherboard and not exposed on the expansion bus. Both dual IRQ and DMA chipsets are cascading which shares the primary pair. In addition to these chipsets, Intel 82284 Clock Driver and Ready Interface and Intel 82288 Bus Controller are to support the microprocessor.

The 24-bit address bus of the 286 expands RAM capacity to 16 MB.

PC DOS 3.0 was included with support for the new AT features, including preliminary kernel support for networking (which was fully supported in a later version 3.x release).

The motherboard includes a battery-backed real-time clock (RTC) using the Motorola MC146818.^[7]^[8] This was an improvement from the PC, which required setting the clock manually or installing an RTC expansion card. The RTC also included a 1024 Hz timer (on IRQ 8), a much finer resolution than the 18 Hz timer on the PC.^[9]

In addition to keeping the time, the RTC includes 50 bytes of CMOS memory which is used to store software-adjustable BIOS parameters. A disk-based BIOS setup program which saved to this memory took the place of the DIP switches used to set system settings on PCs. Most AT clones have the setup program in ROM rather than on disk.

Storage

The standard floppy drive was upgraded to a 1.2 MB <templatestyles src="Fraction/styles.css" />5+1⁄4 inch floppy disk drive (15 sectors of 512 bytes, 80 tracks, two sides), which stored over three times as much data as the 360 KB PC floppy disk, but had compatibility problems with 360k disks (see Problems below). <templatestyles src="Fraction/styles.css" />3+1⁄2 inch floppy drives became available in later ATs.Template:Fact

A 20 MB hard disk drive was included as standard. Early drives were manufactured by Computer Memories and were found to be very unreliable.^[10]

Peripherals

The AT at first shipped with the AT keyboard, initially a new 84-key layout (the 84th key being SysRq). The numerical keypad was now clearly separated from the main key group, and indicator LEDs were added for Caps Lock, Scroll Lock and Num Lock. The AT keyboard uses the same 5-pin DIN connector as the PC keyboard, but a different, bidirectional electrical interface with different keyboard scan codes. The bidirectional interface allows the computer to set the LED indicators on the keyboard, reset the keyboard, set the typematic rate, and other features.

From April 1986, ATs shipped with the Model M keyboard.Template:R

The AT is also equipped with a physical lock that prevents access to the computer by disabling the keyboard and holding the system unit's cover in place.

ATs could be equipped with CGA, MDA, EGA, or PGA video cards.

The 8250 UART from the PC was upgraded to the 16450, but since both chips had single-byte buffers, high-speed serial communication was problematic as with the XT.^[11]

Models

Script error: No such module "Labelled list hatnote".

Template:Table alignment Template:Sort-under

IBM Personal Computer AT models
Template:Verth	Template:Verth	Date announced	Date withdrawn	Bus	Template:Verth	Template:Verth	Processor	Template:Verth	Template:Verth	Template:Verth	FDD	HDD	Notes	Ref(s).
Template:Verth	Template:Verth	Script error: No such module "Date table sorting".	Script error: No such module "Date table sorting".	ISA, 16-bit	8	3	Intel 80286	6	256 KB	512 KB	1.2 MB	Template:CNone		Template:Grid list
Template:Verth	Template:Verth	Script error: No such module "Date table sorting".	Script error: No such module "Date table sorting".	ISA, 16-bit	8	3	Intel 80286	6	512 KB	512 KB	1.2 MB	20 MB		Template:Grid list
Template:Verth	Template:Verth	Script error: No such module "Date table sorting".	Script error: No such module "Date table sorting".	ISA, 16-bit	8	3	Intel 80286	6	512 KB	512 KB	1.2 MB	30 MB		Template:Grid list
Template:Verth	Template:Verth	Script error: No such module "Date table sorting".	Script error: No such module "Date table sorting".	ISA, 16-bit	8	3	Intel 80286	6	512 KB	512 KB	1.2 MB	two 30 MB	Includes controllers for the IBM 4680 Store System	Template:Grid list
Template:Verth	Template:Verth	Script error: No such module "Date table sorting".	Script error: No such module "Date table sorting".	ISA, 16-bit	8	3	Intel 80286	6	512 KB	512 KB	1.2 MB	two 20 MB	Includes controllers for the IBM 4680 Store System	Template:Grid list
Template:Verth	Template:Verth	Script error: No such module "Date table sorting".	Script error: No such module "Date table sorting".	ISA, 16-bit	8	3	Intel 80286	8	512 KB	512 KB	1.2 MB	30 MB		Template:Grid list
Template:Verth	Template:Verth	Script error: No such module "Date table sorting".	Script error: No such module "Date table sorting".	ISA, 16-bit	8	3	Intel 80286	8	512 KB	512 KB	1.2 MB	30 MB	Shipped with Enhanced Keyboard	Template:Grid list
Template:Verth	Template:Verth	Script error: No such module "Date table sorting".	Script error: No such module "Date table sorting".	ISA, 16-bit	8	3	Intel 80286	8	512 KB	512 KB	1.2 MB	Template:CNone	Built to TEMPEST specifications	Template:Grid list
Template:Verth	Template:Verth	Script error: No such module "Date table sorting".	Script error: No such module "Date table sorting".	ISA, 16-bit	8	3	Intel 80286	8	512 KB	512 KB	1.2 MB	30 MB	Built to TEMPEST specifications	Template:Grid list
Template:Verth	Template:Verth	Script error: No such module "Date table sorting".	Script error: No such module "Date table sorting".	ISA, 16-bit	8	3	Intel 80286	6	512 KB	512 KB	1.2 MB	20 MB		Template:Grid list
Template:Verth	Template:Verth	Script error: No such module "Date table sorting".	Script error: No such module "Date table sorting".	ISA, 16-bit	8	3	Intel 80286	6	512 KB	512 KB	1.2 MB	30 MB		Template:Grid list
Template:Verth	Template:Verth	Script error: No such module "Date table sorting".	Script error: No such module "Date table sorting".	ISA, 16-bit	8	3	Intel 80286	6	512 KB	512 KB	1.2 MB	30 MB	1 MB total RAM (peripheral)	Template:Grid list
Template:Verth	Template:Verth	Script error: No such module "Date table sorting".	Script error: No such module "Date table sorting".	ISA, 16-bit	8	3	Intel 80286	6	512 KB	512 KB	1.2 MB	30 MB	1 MB total RAM (peripheral); shipped with Enhanced Keyboard	Template:Grid list

Power supply

The IBM PC AT came with a 192-watt switching power supply, significantly higher than the 130-watt XT power supply.

According to IBM's documentation, in order to function properly, the AT power supply needed a load of at least 7.0 amperes on the +5 V line and a minimum of 2.5 amperes on its +12 V line. The power supply would fail to start unless these minimum load requirements were met, but the AT motherboard did not provide much load on the +12 V line. To solve this problem, entry-level IBM AT models that did not have a hard drive were shipped with a 5-ohm, 50-watt resistor connected on the +12 V line of the hard disk power connector. In normal operation this resistor drew 2.4 amperes (dissipating 28.8 watts), getting fairly hot.^[12]

Problems

In addition to the unreliable hard disk drive,^[13] the high-density floppy disk drives turned out to be problematic. Some ATs came with one high-density (HD) disk drive and one double-density (DD) 360 KB drive. High-density floppy diskette media were compatible only with high-density drives.

There was no way for the disk drive to detect what kind of floppy disk was inserted, and the drives were not distinguished except by an asterisk molded into the 360 KB disk drive faceplate. If the user accidentally used a high-density diskette in the 360 KB drive, it would sometimes work, for a while, but the high-coercivity oxide would take a very weak magnetization from the 360 KB write heads, so reading the diskette would be problematic.

Conversely, the high-density drive's heads had a track width half that of the 360 KB drive, so they were incapable of fully erasing and overwriting tracks written by a 360 KB drive. Overwriting a DD disk that had been written in a DD drive with an HD drive would result in a disk that read on an HD drive, but produced read errors in a DD drive. Whereas a HD read head would only pick up the half track that drive had written, the wider DD read head would pick up the half-track written by the HD drive mixed with the unerased half-track remnant of the track written earlier by a DD drive. Thus, the DD drive would end up reading both new and old information together, causing it to see garbled data.

Clones

The PC AT architecture was functionally an open design, and IBM's efforts to trademark the AT name largely failed. Many 286-based PCs were modeled after it and marketed as AT-compatible. The label also became a standard term in reference to PCs that used the same type of power supply, case, and motherboard layout as the 5170. AT-class became a term describing any machine which supported the same BIOS functions, 80286 or greater processor, 16-bit expansion slots, keyboard interface, 1.2 MB <templatestyles src="Fraction/styles.css" />5+1⁄4 inch floppy disk drives and other defining technical features of the IBM PC AT.

Large companies that had been late to release PC compatibles rushed out AT compatibles, with an estimated 100,000 sold by the end of 1985.^[14] In the United States, popular brands of AT clones included the Tandy 3000, Compaq Deskpro 286, HP Vectra,^[15] Zenith Z-286,^[16] Epson Equity Models II+^[17] and III,^[18] and Commodore PC-30 and PC-40. In Europe, on the other hand, most AT-clones sold were more or less anonymous.

The AT bus became the de facto ISA (Industry Standard Architecture), while PC XT slots were retroactively named 8-bit ISA. The disk interface for the AT, originally a Seagate ST506 compatible interface on IBM's disk controller card, was updated and standardized as ATA ("AT Attachment") by Western Digital and Compaq in 1986, and later renamed PATA (Parallel AT Attachment). The ATA interface was also known as IDE, because the drive controller, instead of being on the interface card, was integrated into the drive (Integrated Drive Electronics).

Reception

By January 1985, AT sales were so strong that IBM and its suppliers could not keep up with demand.^[19] An estimated 350,000 were sold by the end of 1985.Template:R

Creative Computing in December 1984 said "the folks at IBM have done it again". It approved of the "refreshingly standard" keyboard layout, but said that "for most individuals, AT power represents overkill ... a state of the art machine at a top of the line price".^[20] That month the magazine's David H. Ahl chose the AT as the best desktop computer when "price is no object" for 1984, describing it as "an innovative, state-of-the-art computer that has the competition gasping for breath".^[21] An industry analyst wrote in Computerworld in 1985 that the AT's power was evidence of IBM's belief that personal computers were more important for the company than minicomputers.^[22]

Successor

Script error: No such module "Labelled list hatnote". On April 2, 1987, IBM announced the Personal System/2 (PS/2) line, which they marketed as the second-generation of IBM PC. The company promised to continue manufacturing certain models of the first-generation PC, including the AT, for the coming months.^[23] In June 1987, they announced the full withdrawal of the PC/XT and the imminent discontinuation of the PC/AT. The last units of PC/AT (model 339) rolled off the assembly line in July.^[24] While the PC/XT received a directly compatible replacement in the form of the PS/2 Model 30, the AT did not. Users either had to forgo all their 16-bit ISA expansion cards and switch to the proprietary Micro Channel architecture, or settle for a clone if they wanted to upgrade their machine while keeping their expansions. Eventually, in September 1988, IBM announced the PS/2 Model 30 286, which featured an Intel 80286 processor and 16-bit ISA expansion slots,^[25]^[26] serving as the direct replacement for the AT for customers who wanted to buy a true IBM system.^[27]

Timeline

Template:Timeline of the IBM Personal Computer

References

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↑ IBM's official 1986 response to "What percentage of the 20 MB drives in PC ATs have failed?" was "We consider that information to be confidential. However, based on the several customer surveys on the AT that we have conducted for IBM, an overwhelming percentage of AT owners tell us they're satisfied with the system." (questions on page 110, answers on page 111, PC Magazine, April 29, 1986). The article's opening sentence, which reads "If you own an IBM PC AT and your hard disk hasn't crashed yet, don't worry – it probably will." Script error: No such module "citation/CS1". was described as "a rarity in computer journalism" by the Chicago Sun-Times http://www.encyclopedia.com/doc/1P2-3760999.html and the Sun-Times called it a "badly flawed 20-megabyte" disk drive.
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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

External links

Cover story: "IBM brings out the big guns", PC Mag November 13, 1984, pp. 117–133
Wiki entry for PC AT at the Vintage Computer Forums
Historycorner.de – The IBM PC AT (IBM 5170) Template:In lang
IBM 5170 information at www.minuszerodegrees.net

Template:IBM personal computers Template:Authority control

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[13] IBM's official 1986 response to "What percentage of the 20 MB drives in PC ATs have failed?" was "We consider that information to be confidential. However, based on the several customer surveys on the AT that we have conducted for IBM, an overwhelming percentage of AT owners tell us they're satisfied with the system." (questions on page 110, answers on page 111, PC Magazine, April 29, 1986). The article's opening sentence, which reads "If you own an IBM PC AT and your hard disk hasn't crashed yet, don't worry – it probably will." Script error: No such module "citation/CS1". was described as "a rarity in computer journalism" by the Chicago Sun-Times http://www.encyclopedia.com/doc/1P2-3760999.html and the Sun-Times called it a "badly flawed 20-megabyte" disk drive.

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IBM Personal Computer AT: Difference between revisions

Latest revision as of 01:20, 23 December 2025

Contents

Name

History

Features

Storage

Peripherals

Models

Power supply

Problems

Clones

Reception

Successor

Timeline

See also

References

External links

Navigation menu

@@ Line 1: / Line 1: @@
-{{Short description|IBM personal computer released in 1984}}
+{{Short description|Computer released in 1984}}
 {{Use mdy dates|date=May 2024|cs1-dates=y}}
 {{Infobox information appliance
-| name = IBM PC/AT (System Unit 5170)
+| name = IBM PC AT (System Unit 5170)
 | title =
 | aka = IBM AT, PC/AT
 | logo = IBM Personal Computer AT badge recreation.svg
 | logo_upright = 0.5
 | image = File:IBM PC AT.jpg
 | caption =
 | developer =
 | manufacturer = IBM
 | family =
 | type = [[Personal Computer]]
 | generation =
 | releasedate = {{Start date and age|1984|08|14}}<ref>{{cite magazine |last1=Somerson |first1=Paul |title=AT the Party |magazine=PC Magazine |date=November 13, 1984 |page=123 |url=https://books.google.com/books?id=-Ukz6hjZEA4C&pg=PA117 |access-date=July 5, 2014|ref=PC Magazine, November 13, 1984, Page 123}}</ref>
-| lifespan =
+| lifespan = 1984–1987
 | price = Approx. {{US$|6000|1983|round=-2}}
 | discontinued = April 2, 1987<ref name="vintage">{{Cite web |url=http://www.vintage-computer.com/ibmpcat.shtml |title=IBM PC AT at Vintage Computer |access-date=October 20, 2010  |archive-date=August 22, 2020  |archive-url=https://web.archive.org/web/20200822055008/http://www.vintage-computer.com/ibmpcat.shtml |url-status=dead }}</ref>
 | unitssold = >100,000
 | unitsshipped =
 | media =
 | os = {{ubl|[[IBM PC DOS]] 3.0+|OS/2 1.x|[[Interactive Systems Corporation#PC.2FIX|PC/IX]] 1.1|IBM & SCO [[Xenix]]|[[Windows]] 1.0–3.1}}
 | power = 120/240 VAC
 | soc =
-| cpu = [[Intel 80286]] @ 6 and 8&nbsp;MHz
+| cpu = [[Intel 80286]]
 | memory = 256–512&nbsp;[[Kilobyte|KB]] onboard + 3.5&nbsp;[[Megabyte|MB]] with additional memory cards
-| storage = 20&nbsp;MB hard drive<br/>1.2&nbsp;MB HD 5.25" (135&nbsp;mm) floppy drive
+| storage = 20&nbsp;MB hard drive<br />1.2&nbsp;MB HD 5.25" (135&nbsp;mm) floppy drive
 | memory card =
 | display =
 | graphics = [[Color Graphics Adapter|CGA]], [[Enhanced Graphics Adapter|EGA]]
 | sound =
 | input = Parallel, serial
 | controllers =
 | camera =
-| touchpad =
+| connectivity =
-| connectivity =
+| dimensions =
-| platform =
+| weight =
-| service =
+| compatibility =
-| dimensions =
-| weight =
-| topgame =
-| compatibility =
 | predecessor = [[IBM Personal Computer XT]]
 | successor = [[IBM Personal System/2]]
 | related = [[List of IBM Personal Computer models]]
+| CPUspeed = 6 and 8&nbsp;MHz
 }}
-The '''IBM Personal Computer AT''' (model 5170, abbreviated as '''IBM AT''' or '''PC/AT''') was released in 1984 as the fourth model in the [[IBM Personal Computer]] line, following the [[IBM Personal Computer/XT|IBM PC/XT]] and its [[IBM Portable Personal Computer|IBM Portable PC]] variant. It was designed around the [[Intel 80286]] [[microprocessor]].
+The '''IBM Personal Computer AT''' (model 5170, abbreviated as '''IBM AT''' or '''PC/AT''') was released in 1984 as the fourth model in the [[IBM Personal Computer]] line, following the [[IBM Personal Computer XT|IBM PC XT]] and its [[IBM Portable Personal Computer|IBM Portable PC]] variant. It was designed around the [[Intel 80286]] [[microprocessor]].
 == Name ==
@@ Line 54: / Line 51: @@
 ==History==
 [[IBM]]'s 1984 introduction of the AT was seen as an unusual move for the company, which typically waited for competitors to release new products before producing its own models. At $4,000–6,000, it was only slightly more expensive than considerably slower IBM models. The announcement surprised rival executives, who admitted that matching IBM's prices would be difficult. No major competitor showed a comparable computer at [[COMDEX]] Las Vegas that year.<ref name="sanger19841119">{{Cite news |url=https://www.nytimes.com/1984/11/19/business/ibm-entry-unchallenged-at-show.html |title=I.B.M. Entry Unchallenged at Show |last=Sanger |first=David E. |date=November 19, 1984 |work=The New York Times |access-date=July 3, 2017 |language=en-US |issn=0362-4331}}</ref>
-[[File:IBM 5170 with Floor Standing Enclosure.jpg|thumb|IBM 5170 with Floor Standing Enclosure<ref>{{Cite web |title=IBM PC-AT - UvA Computer Museum catalogue |url=https://ub.fnwi.uva.nl/computermuseum/pcat.html#close |access-date=July 15, 2023 |website=[[University of Amsterdam]]}}</ref> and compatible non-IBM display]]
+In April 1986 IBM revised the AT, increasing the speed of its [[Intel 80286]] CPU from 6 to 8 MHz.<ref name="lewis19860506">{{Cite news |last=Lewis |first=Peter H. |date=1986-05-06 |title=Clone War Escalates |url=https://www.nytimes.com/1986/05/06/science/peripherals-clone-war-escalates.html |work=The New York Times |pages=C8}}</ref>
+[[File:IBM 5170 with Floor Standing Enclosure.jpg|thumb|IBM 5170 with Floor Standing Enclosure<ref>{{Cite web |title=IBM PC-AT – UvA Computer Museum catalogue |url=https://ub.fnwi.uva.nl/computermuseum/pcat.html#close |access-date=July 15, 2023 |website=[[University of Amsterdam]]}}</ref> and compatible non-IBM display]]
 == Features ==
@@ Line 65: / Line 65: @@
 [[PC DOS]] 3.0 was included with support for the new AT features, including preliminary kernel support for networking (which was fully supported in a later version 3.x release).
-The motherboard includes a battery-backed [[real-time clock]] (RTC) using the Motorola MC146818.<ref name="Horan2013">{{cite book|author=Brendan Horan|url=https://books.google.com/books?id=PSonZP4Nj5sC&pg=PA146|title=Practical Raspberry Pi|date=March 26, 2013|publisher=Apress|isbn=978-1-4302-4972-6|page=146}}</ref><ref name="ShanleyAnderson1995">{{cite book|author-last1=Shanley|author-first1=Tom|url=https://archive.org/details/ISA_System_Architecture|title=ISA System Architecture|author-last2=Anderson|author-first2=Don|date=1995|publisher=Mindshare, Inc. / [[Addison-Wesley Publishing Company]]|isbn=0-201-40996-8|editor-last=Swindle|editor-first=John|edition=3|pages=[https://archive.org/details/ISA_System_Architecture/page/n451 441]–444}}</ref> This was an improvement from the PC, which required setting the clock manually or installing an RTC expansion card. The RTC also included a 1024&nbsp;Hz timer (on IRQ 8), a much finer resolution than the 18&nbsp;Hz timer on the PC.<ref name="Austerlitz2002">{{cite book|author=Howard Austerlitz|url=https://books.google.com/books?id=gK4DxMaqmYYC&pg=PA90|title=Data Acquisition Techniques Using PCs|publisher=Academic Press|year=2002|isbn=978-0-08-053025-3|pages=90–91}}</ref>
+The motherboard includes a battery-backed [[real-time clock]] (RTC) using the Motorola MC146818.<ref name="Horan2013">{{cite book|author=Brendan Horan|url=https://books.google.com/books?id=PSonZP4Nj5sC&pg=PA146|title=Practical Raspberry Pi|year=2013|publisher=Apress|isbn=978-1-4302-4972-6|page=146}}</ref><ref name="ShanleyAnderson1995">{{cite book|author-last1=Shanley|author-first1=Tom|url=https://archive.org/details/ISA_System_Architecture|title=ISA System Architecture|author-last2=Anderson|author-first2=Don|date=1995|publisher=Mindshare, Inc. / [[Addison-Wesley Publishing Company]]|isbn=0-201-40996-8|editor-last=Swindle|editor-first=John|edition=3|pages=[https://archive.org/details/ISA_System_Architecture/page/n451 441]–444}}</ref> This was an improvement from the PC, which required setting the clock manually or installing an RTC expansion card. The RTC also included a 1024&nbsp;Hz timer (on IRQ 8), a much finer resolution than the 18&nbsp;Hz timer on the PC.<ref name="Austerlitz2002">{{cite book|author=Howard Austerlitz|url=https://books.google.com/books?id=gK4DxMaqmYYC&pg=PA90|title=Data Acquisition Techniques Using PCs|publisher=Academic Press|year=2002|isbn=978-0-08-053025-3|pages=90–91}}</ref>
 In addition to keeping the time, the RTC includes 50 bytes of [[CMOS memory]] which is used to store software-adjustable [[BIOS]] parameters. A disk-based BIOS setup program which saved to this memory took the place of the [[DIP switch]]es used to set system settings on PCs. Most AT clones have the setup program in [[Read-only memory|ROM]] rather than on disk.
@@ Line 75: / Line 75: @@
 === Peripherals ===
-The AT included the [[AT keyboard]], initially a new 84-key layout (the 84th key being [[System request|SysRq]]). The numerical keypad was now clearly separated from the main key group, and indicator [[light-emitting diode|LEDs]] were added for Caps Lock, Scroll Lock and Num Lock. The AT keyboard uses the same 5-pin [[DIN connector]] as the PC keyboard, but a different, bidirectional electrical interface with different keyboard [[scan code]]s. The bidirectional interface allows the computer to set the LED indicators on the keyboard, reset the keyboard, set the typematic rate, and other features. Later ATs included 101-key keyboards, e.g. the [[Model M keyboard]].
+The AT at first shipped with the [[AT keyboard]], initially a new 84-key layout (the 84th key being [[System request|SysRq]]). The numerical keypad was now clearly separated from the main key group, and indicator [[light-emitting diode|LEDs]] were added for Caps Lock, Scroll Lock and Num Lock. The AT keyboard uses the same 5-pin [[DIN connector]] as the PC keyboard, but a different, bidirectional electrical interface with different keyboard [[scan code]]s. The bidirectional interface allows the computer to set the LED indicators on the keyboard, reset the keyboard, set the typematic rate, and other features.
+From April 1986, ATs shipped with the [[Model M keyboard]].{{r|lewis19860506}}
 The AT is also equipped with a [[computer lock|physical lock]] that prevents access to the computer by disabling the keyboard and holding the system unit's cover in place.
@@ Line 85: / Line 87: @@
 === Models ===
 {{Main|List of IBM Personal Computer models}}
-{| class="wikitable sortable sticky-header sort-under"
-|-
+{{table alignment}}
-|+ IBM Personal Computer models
+{{sort-under}}
-! Type
+{| class="wikitable sortable sticky-header sort-under col3right col4right col12right"
-! IBM {{abbr|P/N|part number}}
+|-
+|+ IBM Personal Computer AT models
+! {{verth|va=middle|Type}}
+! {{verth|va=middle|IBM {{abbr|P/N|part number}}}}
 ! Date announced
 ! Date withdrawn
 ! Bus
-! {{abbr|No.|Number}} of<br />slots
+! {{verth|va=middle|{{abbr|No.|Number}} of slots}}
-! {{abbr|No.|Number}} of<br />bays
+! {{verth|va=middle|{{abbr|No.|Number}} of bays}}
 ! Processor
-! Clock<br />speed<br />{{small|(MHz)}}
+! {{verth|va=middle|Clock speed<br />{{small|(MHz)}}}}
-! Stock onboard RAM<br />{{small|(KB)}}
+! {{verth|va=middle|Stock onboard RAM<br />{{small|(KB)}}}}
-! Maximum onboard RAM<br />{{small|(KB)}}
+! {{verth|va=middle|Maximum onboard RAM<br />{{small|(KB)}}}}
 ! {{abbr|FDD|Floppy disk drive}}
 ! {{abbr|HDD|Hard disk drive}}
@@ Line 104: / Line 109: @@
 ! Ref(s).
 |-
-| AT
+| {{verth|va=middle|AT}}
-| 5170-068
+| {{verth|va=middle|5170-068}}
 | {{date table sorting|1984|08|14|format=my}}
 | {{date table sorting|1987|06|30|format=my}}
@@ Line 116: / Line 121: @@
 | 512&nbsp;KB
 | 1.2&nbsp;MB
-| none
+| {{CNone|none}}
-|
+| &nbsp;
-| <ref name=ibmref40>{{cite book | date=April 6, 1987 | url=https://bitsavers.org/pdf/ibm/pc/PS2_and_IBM_PC_Product_Reference_Version_4.0_Apr87.pdf#page=244 | title=IBM Personal System/2 and IBM Personal Computer Product Reference | edition=4.0 | publisher=International Business Machines Corporation | via=[[Bitsavers]]}}</ref>{{rp|49}}<ref name=pcweekatannounced>{{cite journal | last=Whitmore | first=Sam | date=August 14, 1984 | url=https://link.gale.com/apps/doc/A573108/GPS?sid=wikipedia | title=IBM's New Generation: The PC AT: AT Hikes CPU Speed Sixfold, Memory Fivefold | journal=PC Week | publisher=Ziff-Davis | volume=1 | issue=32 | page=1 | via=Gale | quote=The IBM PC AT Base Model 68, with one 1.2-megabyte floppy-disk drive, will sell for $3,995, according to a source close to IBM. Model 99, with a 1.2-megabyte floppy-disk drive and a 20-megabyte hard disk, will cost $5,795. Both models will use a 6-MHz 80286 microprocessor.}}</ref><ref name=atdiscontinued>{{cite journal | last=Abruzzese | first=George | date=June 29, 1987 | url=https://books.google.com/books?id=xjAEAAAAMBAJ&pg=PA1 | title=IBM Plans to Terminate Remainder of PC Line | journal=InfoWorld | publisher=IDG Publications | volume=9 | issue=26 | pages=1, 69 | via=Google Books}}</ref>
+| {{grid list|columns=2|<ref name=ibmref40>{{cite book | date=April 6, 1987 | url=https://bitsavers.org/pdf/ibm/pc/PS2_and_IBM_PC_Product_Reference_Version_4.0_Apr87.pdf#page=244 | title=IBM Personal System/2 and IBM Personal Computer Product Reference | edition=4.0 | publisher=International Business Machines Corporation | via=[[Bitsavers]]}}</ref>{{rp|49}}|<ref name=pcweekatannounced>{{cite journal | last=Whitmore | first=Sam | date=August 14, 1984 | url=https://link.gale.com/apps/doc/A573108/GPS?sid=wikipedia | title=IBM's New Generation: The PC AT: AT Hikes CPU Speed Sixfold, Memory Fivefold | journal=PC Week | publisher=Ziff-Davis | volume=1 | issue=32 | page=1 | via=Gale | quote=The IBM PC AT Base Model 68, with one 1.2-megabyte floppy-disk drive, will sell for $3,995, according to a source close to IBM. Model 99, with a 1.2-megabyte floppy-disk drive and a 20-megabyte hard disk, will cost $5,795. Both models will use a 6-MHz 80286 microprocessor.}}</ref>|<ref name=atdiscontinued>{{cite journal | last=Abruzzese | first=George | date=June 29, 1987 | url=https://books.google.com/books?id=xjAEAAAAMBAJ&pg=PA1 | title=IBM Plans to Terminate Remainder of PC Line | journal=InfoWorld | publisher=IDG Publications | volume=9 | issue=26 | pages=1, 69 | via=Google Books}}</ref>}}
 |-
-| AT
+| {{verth|va=middle|AT}}
-| 5170-099
+| {{verth|va=middle|5170-099}}
 | {{date table sorting|1984|08|14|format=my}}
 | {{date table sorting|1987|06|30|format=my}}
@@ Line 133: / Line 138: @@
 | 1.2&nbsp;MB
 | 20&nbsp;MB
-|
+| &nbsp;
-| <ref name=ibmref40 />{{rp|236}}<ref name=pcweekatannounced /><ref name=atdiscontinued />
+| {{grid list|columns=2|<ref name=ibmref40 />{{rp|236}}|<ref name=pcweekatannounced />|<ref name=atdiscontinued />}}
 |-
-| AT
+| {{verth|va=middle|AT}}
-| 5170-239
+| {{verth|va=middle|5170-239}}
 | {{date table sorting|1985|10|01|format=my}}
 | {{date table sorting|1986|09|02|format=my}}
@@ Line 149: / Line 154: @@
 | 1.2&nbsp;MB
 | 30&nbsp;MB
-|
+| &nbsp;
-| <ref name=ibmref40 />{{rp|236}}<ref name=at30mb>{{cite journal | last=Kuzbyt | first=Bob | date=October 7, 1985 | url=https://link.gale.com/apps/doc/A3972202/GPS?sid=wikipedia | title=IBM introduces 30-MB 5.25-inch Winchester disk drive for AT | journal=Electronic News | publisher= Sage Publications | volume=31 | page=26 | via=Gale}}</ref><ref name=Ristelhueber>{{cite journal | last=Ristelhueber | first=Robert | author2=Ira Sager | date=September 8, 1986 | url=https://link.gale.com/apps/doc/A4398861/GPS?sid=wikipedia | title=4 PC suppliers add 286 units in battle with compatibles | journal=Electronic News | publisher=Sage Publications | volume=32 | pages=1 ''et seq'' | via=Gale}}</ref>
+| {{grid list|columns=2|<ref name=ibmref40 />{{rp|236}}|<ref name=at30mb>{{cite journal | last=Kuzbyt | first=Bob | date=October 7, 1985 | url=https://link.gale.com/apps/doc/A3972202/GPS?sid=wikipedia | title=IBM introduces 30-MB 5.25-inch Winchester disk drive for AT | journal=Electronic News | publisher= Sage Publications | volume=31 | page=26 | via=Gale}}</ref>|<ref name=Ristelhueber>{{cite journal | last=Ristelhueber | first=Robert | author2=Ira Sager | date=September 8, 1986 | url=https://link.gale.com/apps/doc/A4398861/GPS?sid=wikipedia | title=4 PC suppliers add 286 units in battle with compatibles | journal=Electronic News | publisher=Sage Publications | volume=32 | pages=1 ''et seq'' | via=Gale}}</ref>}}
 |-
-| AT
+| {{verth|va=middle|AT}}
-| 5170-839
+| {{verth|va=middle|5170-839}}
 | {{date table sorting|1986|01|08|format=my}}
 | {{date table sorting|1987|06|30|format=my}}
@@ Line 164: / Line 169: @@
 | 512&nbsp;KB
 | 1.2&nbsp;MB
-| two&nbsp;30&nbsp;MB
+| two 30&nbsp;MB
 | Includes controllers for the [[IBM 4680|IBM 4680 Store System]]
-| <ref name=ibmref40 />{{rp|236}}<ref name=at4680>{{cite journal | last=Whitmore | first=Sam | date=January 14, 1986 | url=https://link.gale.com/apps/doc/A656864/GPS?sid=wikipedia | title=IBM Debuts PC AT-Based Point-of-Sale Retail System | journal=PC Week | publisher=Ziff-Davis | volume=3 | issue=2 | page=8 | via=Gale}}</ref><ref name=atdiscontinued />
+| {{grid list|columns=2|<ref name=ibmref40 />{{rp|236}}|<ref name=at4680>{{cite journal | last=Whitmore | first=Sam | date=January 14, 1986 | url=https://link.gale.com/apps/doc/A656864/GPS?sid=wikipedia | title=IBM Debuts PC AT-Based Point-of-Sale Retail System | journal=PC Week | publisher=Ziff-Davis | volume=3 | issue=2 | page=8 | via=Gale}}</ref>|<ref name=atdiscontinued />}}
 |-
-| AT
+| {{verth|va=middle|AT}}
-| 5170-899
+| {{verth|va=middle|5170-899}}
 | {{date table sorting|1986|01|08|format=my}}
 | {{date table sorting|1987|06|30|format=my}}
@@ Line 180: / Line 185: @@
 | 512&nbsp;KB
 | 1.2&nbsp;MB
-| two&nbsp;20&nbsp;MB
+| two 20&nbsp;MB
 | Includes controllers for the [[IBM 4680|IBM 4680 Store System]]
-| <ref name=ibmref40 />{{rp|236}}<ref name=at4680 /><ref name=atdiscontinued />
+| {{grid list|columns=2|<ref name=ibmref40 />{{rp|236}}|<ref name=at4680 />|<ref name=atdiscontinued />}}
 |-
-| AT
+| {{verth|va=middle|AT}}
-| 5170-319
+| {{verth|va=middle|5170-319}}
 | {{date table sorting|1986|04|02|format=my}}
 | {{date table sorting|1987|06|30|format=my}}
@@ Line 197: / Line 202: @@
 | 1.2&nbsp;MB
 | 30&nbsp;MB
-|
+| &nbsp;
-| <ref name=ibmref40 />{{rp|236}}<ref name=at8mhz>{{cite journal | last=Whitmore | first=Sam | date=April 1, 1986 | url=https://link.gale.com/apps/doc/A666974/GPS?sid=wikipedia | title=IBM meetings said to key on new products | journal=PC Week | publisher=Ziff-Davis | volume=3 | issue=13 | page=1 | via=Gale}}</ref><ref name=atdiscontinued />
+| {{grid list|columns=2|<ref name=ibmref40 />{{rp|236}}|<ref name=at8mhz>{{cite journal | last=Whitmore | first=Sam | date=April 1, 1986 | url=https://link.gale.com/apps/doc/A666974/GPS?sid=wikipedia | title=IBM meetings said to key on new products | journal=PC Week | publisher=Ziff-Davis | volume=3 | issue=13 | page=1 | via=Gale}}</ref>|<ref name=atdiscontinued />}}
 |-
-| AT
+| {{verth|va=middle|AT}}
-| 5170-339
+| {{verth|va=middle|5170-339}}
 | {{date table sorting|1986|04|02|format=my}}
 | {{date table sorting|1987|07|format=my}}
@@ Line 214: / Line 219: @@
 | 30&nbsp;MB
 | Shipped with Enhanced Keyboard
-| <ref name=ibmref40 />{{rp|236}}<ref name=at8mhz /><ref name=atdiscontinued />
+| {{grid list|columns=2|<ref name=ibmref40 />{{rp|236}}|<ref name=at8mhz />|<ref name=atdiscontinued />}}
 |-
-| AT
+| {{verth|va=middle|AT}}
-| 5171-168
+| {{verth|va=middle|5171-168}}
 | {{date table sorting|1986|10|21|format=my}}
 | {{date table sorting|1987|06|30|format=my}}
@@ Line 228: / Line 233: @@
 | 512&nbsp;KB
 | 1.2&nbsp;MB
-| none
+| {{CNone|none}}
 | Built to [[Tempest (codename)|TEMPEST]] specifications
-| <ref name=ibmref40 />{{rp|64}}<ref name=atdiscontinued />
+| {{grid list|columns=2|<ref name=ibmref40 />{{rp|64}}|<ref name=atdiscontinued />}}
 |-
-| AT
+| {{verth|va=middle|AT}}
-| 5171-339
+| {{verth|va=middle|5171-339}}
 | {{date table sorting|1986|10|21|format=my}}
 | {{date table sorting|1987|07|format=my}}
@@ Line 246: / Line 251: @@
 | 30&nbsp;MB
 | Built to [[Tempest (codename)|TEMPEST]] specifications
-| <ref name=ibmref40 />{{rp|64}}<ref name=atdiscontinued />
+| {{grid list|columns=2|<ref name=ibmref40 />{{rp|64}}|<ref name=atdiscontinued />}}
 |-
-| [[IBM Personal Computer AT/370|AT/370]]
+| {{verth|va=middle|[[IBM Personal Computer AT/370|AT/370]]}}
-| 5170-599
+| {{verth|va=middle|5170-599}}
 | {{date table sorting|1984|10|25|format=my}}
 | {{date table sorting|1987|04|02|format=my}}
@@ Line 261: / Line 266: @@
 | 1.2&nbsp;MB
 | 20&nbsp;MB
 |
-| <ref name=ibmref40 />{{rp|202}}<ref name=givesup>{{cite journal | date=April 13, 1987 | url=https://techmonitor.ai/technology/ibm_gives_up_on_the_personal_xt_at370 | title=IBM Gives Up on the Personal XT/, AT/370 | journal=Computer Business Review | publisher=New Statesman Media Group | archiveurl=https://archive.today/20230920021426/https://techmonitor.ai/technology/ibm_gives_up_on_the_personal_xt_at370 | archivedate=September 20, 2023}}</ref>
+| {{grid list|columns=2|<ref name=ibmref40 />{{rp|202}}|<ref name=givesup>{{cite journal | date=April 13, 1987 | url=https://techmonitor.ai/technology/ibm_gives_up_on_the_personal_xt_at370 | title=IBM Gives Up on the Personal XT/, AT/370 | journal=Computer Business Review | publisher=New Statesman Media Group | archiveurl=https://archive.today/20230920021426/https://techmonitor.ai/technology/ibm_gives_up_on_the_personal_xt_at370 | archivedate=September 20, 2023}}</ref>}}
 |-
-| [[IBM Personal Computer AT/370|AT/370]]
+| {{verth|va=middle|[[IBM Personal Computer AT/370|AT/370]]}}
-| 5170-739
+| {{verth|va=middle|5170-739}}
 | {{date table sorting|1985|10|01|format=my}}
 | {{date table sorting|1987|04|02|format=my}}
@@ Line 277: / Line 282: @@
 | 1.2&nbsp;MB
 | 30&nbsp;MB
-|
+| &nbsp;
-| <ref name=ibmref40 />{{rp|202}}<ref name=sandker>{{cite journal | last=Sandker | first=C. | date=October 8, 1985 | url=https://link.gale.com/apps/doc/A649986/GPS?sid=wikipedia | title=IBM Delivers New PC AT Featuring 30M-Byte Disk: Sets a Price Tag of $5,995 | journal=PC Week | publisher=Ziff-Davis | volume=2 | issue=40 | page=1 | via=Gale}}</ref><ref name=pctjv4n13>{{cite journal | date=1987 | url=https://archive.org/details/PC_Tech_Journal_vol04_n13/page/69/ | title=Desktop Systems | journal=PC Tech Journal | publisher=Ziff-Davis | volume=4 | issue=13 | page=69 | via=the Internet Archive}}</ref><ref name=givesup />
+| {{grid list|columns=2|<ref name=ibmref40 />{{rp|202}}|<ref name=sandker>{{cite journal | last=Sandker | first=C. | date=October 8, 1985 | url=https://link.gale.com/apps/doc/A649986/GPS?sid=wikipedia | title=IBM Delivers New PC AT Featuring 30M-Byte Disk: Sets a Price Tag of $5,995 | journal=PC Week | publisher=Ziff-Davis | volume=2 | issue=40 | page=1 | via=Gale}}</ref>|<ref name=pctjv4n13>{{cite journal | date=1987 | url=https://archive.org/details/PC_Tech_Journal_vol04_n13/page/69/ | title=Desktop Systems | journal=PC Tech Journal | publisher=Ziff-Davis | volume=4 | issue=13 | page=69 | via=the Internet Archive}}</ref>|<ref name=givesup />}}
 |-
-| [[IBM Personal Computer AT/370|AT/370]]
+| {{verth|va=middle|[[IBM Personal Computer AT/370|AT/370]]}}
-| 5170-919
+| {{verth|va=middle|5170-919}}
 | {{date table sorting|1986|04|02|format=my}}
 | {{date table sorting|1987|04|02|format=my}}
@@ Line 294: / Line 299: @@
 | 30&nbsp;MB
 | 1&nbsp;MB total RAM (peripheral)
-| <ref name=ibmref40 />{{rp|57}}<ref name=prnewswireat370>{{cite web | last=Kennedy | first=Don | date=April 2, 1986 | url=https://link.gale.com/apps/doc/A4196480/GPS?sid=wikipedia | title=IBM has boosted the processor speed and storage capacity of its personal computer models | publisher=PR Newswire | page=NYPR14C | via=Gale}}</ref><ref name=givesup />
+| {{grid list|columns=2|<ref name=ibmref40 />{{rp|57}}|<ref name=prnewswireat370>{{cite web | last=Kennedy | first=Don | date=April 2, 1986 | url=https://link.gale.com/apps/doc/A4196480/GPS?sid=wikipedia | title=IBM has boosted the processor speed and storage capacity of its personal computer models | publisher=PR Newswire | page=NYPR14C | via=Gale}}</ref>|<ref name=givesup />}}
 |-
-| [[IBM Personal Computer AT/370|AT/370]]
+| {{verth|va=middle|[[IBM Personal Computer AT/370|AT/370]]}}
-| 5170-939
+| {{verth|va=middle|5170-939}}
 | {{date table sorting|1986|04|02|format=my}}
 | {{date table sorting|1987|04|02|format=my}}
@@ Line 310: / Line 315: @@
 | 30&nbsp;MB
 | 1&nbsp;MB total RAM (peripheral); shipped with Enhanced Keyboard
-| <ref name=ibmref40 />{{rp|57}}<ref name=prnewswireat370/><ref name=givesup />
+| {{grid list|columns=2|<ref name=ibmref40 />{{rp|57}}|<ref name=prnewswireat370/>|<ref name=givesup />}}
 |}
@@ Line 319: / Line 324: @@
 == Problems ==
-In addition to the unreliable hard disk drive,<ref>IBM's official 1986 response to "What percentage of the 20 MB drives in PC ATs have failed?" was "We consider that information to be confidential. However, based on the several customer surveys on the AT that we have conducted for IBM, an overwhelming percentage of AT owners tell us they're satisfied with the system." (questions on page 110, answers on page 111, PC Magazine, April 29, 1986).  The article's opening sentence, which reads "If you own an IBM PC AT and your hard disk hasn't crashed yet, don't worry -- it probably will."  {{Cite web |url=http://www.highbeam.com/doc/1P2-3760999.html |title=Archived copy |access-date=2010-06-30  |archive-date=2012-11-04  |archive-url=https://web.archive.org/web/20121104075857/http://www.highbeam.com/doc/1P2-3760999.html |url-status=dead }} was described as "a rarity in computer journalism" by the Chicago Sun-Times http://www.encyclopedia.com/doc/1P2-3760999.html and the Sun-Times called it a "badly flawed 20-megabyte" disk drive.</ref> the high-density floppy disk drives turned out to be problematic.  Some ATs came with one high-density (HD) disk drive and one double-density (DD) 360&nbsp;KB drive. High-density floppy diskette media were compatible only with high-density drives.
+In addition to the unreliable hard disk drive,<ref>IBM's official 1986 response to "What percentage of the 20 MB drives in PC ATs have failed?" was "We consider that information to be confidential. However, based on the several customer surveys on the AT that we have conducted for IBM, an overwhelming percentage of AT owners tell us they're satisfied with the system." (questions on page 110, answers on page 111, PC Magazine, April 29, 1986).  The article's opening sentence, which reads "If you own an IBM PC AT and your hard disk hasn't crashed yet, don't worry – it probably will."  {{Cite web |url=http://www.highbeam.com/doc/1P2-3760999.html |title=IBM benchmark faces revolt from users of hard disk drive - Chicago Sun-Times &#124; HighBeam Research |access-date=2010-06-30  |archive-date=2012-11-04  |archive-url=https://web.archive.org/web/20121104075857/http://www.highbeam.com/doc/1P2-3760999.html |url-status=dead }} was described as "a rarity in computer journalism" by the Chicago Sun-Times http://www.encyclopedia.com/doc/1P2-3760999.html and the Sun-Times called it a "badly flawed 20-megabyte" disk drive.</ref> the high-density floppy disk drives turned out to be problematic.  Some ATs came with one high-density (HD) disk drive and one double-density (DD) 360&nbsp;KB drive. High-density floppy diskette media were compatible only with high-density drives.
 There was no way for the disk drive to detect what kind of floppy disk was inserted, and the drives were not distinguished except by an asterisk molded into the 360&nbsp;KB disk drive faceplate. If the user accidentally used a high-density diskette in the 360&nbsp;KB drive, it would sometimes work, for a while, but the high-[[coercivity]] oxide would take a very weak magnetization from the 360&nbsp;KB write heads, so reading the diskette would be problematic.
@@ Line 328: / Line 333: @@
 The PC AT architecture was functionally an open design, and IBM's efforts to [[trademark]] the AT name largely failed. Many 286-based PCs were modeled after it and marketed as ''AT-compatible''. The label also became a standard term in reference to PCs that used the same type of power supply, case, and motherboard layout as the 5170. ''AT-class'' became a term describing any machine which supported the same BIOS functions, 80286 or greater processor, 16-bit expansion slots, keyboard interface, 1.2&nbsp;MB {{frac|5|1|4}} inch floppy disk drives and other defining technical features of the IBM PC AT.
-Large companies that had been late to release PC compatibles rushed out AT compatibles, with an estimated 100,000 sold by the end of 1985.<ref name="bright19860623">{{Cite magazine |last=Bright |first=David |date=1986-06-23 |title=AT compatibles: Systems vendors push to give single-source option |url=https://books.google.com/books?id=mop2UUCt4kIC&pg=PA1#v=onepage&q&f=true |access-date=2025-05-17 |magazine=Computerworld |pages=1, 14-15 |volume=XX |issue=25}}</ref> In the United States, popular brands of AT clones included the [[Tandy 3000]], [[Compaq Deskpro]] 286, [[Hewlett-Packard|HP]] Vectra,<ref>{{cite web |title=HP Computer Museum |url=http://hpmuseum.net/display_item.php?hw=125 |website=hpmuseum dot net |publisher=BGImages Australia |access-date=July 9, 2020}}</ref> [[Zenith Data Systems#Computers|Zenith]] Z-286,<ref>{{cite magazine |title=Zenith Innovates Again |magazine=PC Magazine |date=August 1989 |page=375 |url=https://books.google.com/books?id=fSMW_RgWwIgC&q=zenith+z-286&pg=PT362 |via=Google Books |author=Zenith Data Systems}}</ref> [[Epson Equity]] Models II+<ref>{{cite web |title=Equity II+ Product Info |url=https://files.support.epson.com/pdf/e2p___/e2p___pg.pdf |website=files.support.epson.com |publisher=Epson USA |access-date=July 8, 2020}}</ref> and III,<ref>{{cite web |title=Equity III Product Info |url=http://files.support.epson.com/pdf/e3p___/e3p___pg.pdf|website=files.support.epson.com |publisher=Epson USA |access-date=July 8, 2020}}</ref> and [[Commodore PC compatible systems#Models|Commodore PC-30 and PC-40]]. In Europe, on the other hand, most AT-clones sold were more or less anonymous.
+Large companies that had been late to release PC compatibles rushed out AT compatibles, with an estimated 100,000 sold by the end of 1985.<ref name="bright19860623">{{Cite magazine |last=Bright |first=David |date=1986-06-23 |title=AT compatibles: Systems vendors push to give single-source option |url=https://books.google.com/books?id=mop2UUCt4kIC&pg=PA1 |access-date=2025-05-17 |magazine=Computerworld |pages=1, 14–15 |volume=XX |issue=25}}</ref> In the United States, popular brands of AT clones included the [[Tandy 3000]], [[Compaq Deskpro]] 286, [[Hewlett-Packard|HP]] Vectra,<ref>{{cite web |title=HP Computer Museum |url=http://hpmuseum.net/display_item.php?hw=125 |website=hpmuseum dot net |publisher=BGImages Australia |access-date=July 9, 2020}}</ref> [[Zenith Data Systems#Computers|Zenith]] Z-286,<ref>{{cite magazine |title=Zenith Innovates Again |magazine=PC Magazine |date=August 1989 |page=375 |url=https://books.google.com/books?id=fSMW_RgWwIgC&q=zenith+z-286&pg=PT362 |via=Google Books |author=Zenith Data Systems}}</ref> [[Epson Equity]] Models II+<ref>{{cite web |title=Equity II+ Product Info |url=https://files.support.epson.com/pdf/e2p___/e2p___pg.pdf |website=files.support.epson.com |publisher=Epson USA |access-date=July 8, 2020}}</ref> and III,<ref>{{cite web |title=Equity III Product Info |url=http://files.support.epson.com/pdf/e3p___/e3p___pg.pdf|website=files.support.epson.com |publisher=Epson USA |access-date=July 8, 2020}}</ref> and [[Commodore PC compatible systems#Models|Commodore PC-30 and PC-40]]. In Europe, on the other hand, most AT-clones sold were more or less anonymous.
 The AT bus became the de facto ISA ([[Industry Standard Architecture]]), while PC XT slots were retroactively named ''8-bit ISA''. The disk interface for the AT, originally a Seagate [[ST506]] compatible interface on IBM's disk controller card, was updated and standardized as ATA ("AT Attachment") by [[Western Digital]] and [[Compaq]] in 1986, and later renamed PATA ([[Parallel ATA|Parallel AT Attachment]]). The ATA interface was also known as IDE, because the drive controller, instead of being on the interface card, was integrated into the drive ([[Parallel ATA#IDE and ATA-1|Integrated Drive Electronics]]).
@@ Line 339: / Line 344: @@
 ==Successor==
 {{main|IBM PS/2 Model 30 286}}
-On April 2, 1987, IBM announced the [[IBM Personal System/2|Personal System/2]] (PS/2) line, which they marketed as the second-generation of IBM PC. The company promised to continue manufacturing certain models of the first-generation PC, including the AT, for the coming months.<ref name=Potts1987>{{cite news | last=Potts | first=Mark | date=April 3, 1987 | url=https://www.proquest.com/docview/306890384/ | title=New IBM Computers Unveiled | newspaper=The Washington Post | page=F1 | via=ProQuest}}</ref> In June 1987, they announced the full withdrawal of the PC/XT and the imminent discontinuation of the PC/AT. The last units of PC/AT (model 339) rolled off the assembly line in July.<ref name=atdiscontinued/> While the PC/XT received a directly compatible replacement in the form of the [[IBM PS/2 Model 30|PS/2 Model 30]], the AT did not. Users either had to forgo all their 16-bit ISA expansion cards and switch to the proprietary [[Micro Channel architecture]], or settle for a clone if they wanted to upgrade their machine while keeping their expansions. Eventually, in September 1988, IBM announced the [[IBM PS/2 Model 30 286|PS/2 Model 30 286]], which featured an Intel 80286 processor and 16-bit ISA expansion slots,<ref name=Reuters1988>{{cite news | agency=Reuters | date=September 14, 1988 | url=https://www.proquest.com/docview/389348570/ | title=IBM Adding PS/2 Computer Compatible with AT Models | work=Sun-Sentinel | page=3D | via=ProQuest}}</ref><ref name=Miller1988>{{cite journal | last=Miller | first=Michael W. | date=September 14, 1988 | url=https://www.proquest.com/docview/398059991/ | title=IBM Introduces Low-end PC Aimed at Single Users | journal=The Wall Street Journal | publisher=Dow Jones & Company | page=1 | via=ProQuest}}</ref> serving as the direct replacement for the AT for customers who wanted to buy a true IBM system.<ref name=Rosch1989>{{cite journal | last=Rosch | first=Winn L. | date=January 17, 1989 | url=https://books.google.com/books?id=C6VFJIbxX7MC&pg=PA267 | title=What's Old Is New | journal=PC Magazine | publisher=Ziff-Davis | volume=8 | issue=1 | pages=259–272 | via=Google Books}}</ref>
+On April 2, 1987, IBM announced the [[IBM Personal System/2|Personal System/2]] (PS/2) line, which they marketed as the second-generation of IBM PC. The company promised to continue manufacturing certain models of the first-generation PC, including the AT, for the coming months.<ref name=Potts1987>{{cite news | last=Potts | first=Mark | date=April 3, 1987 | url=https://www.proquest.com/docview/306890384 | title=New IBM Computers Unveiled | newspaper=The Washington Post | page=F1 |id={{ProQuest|306890384}}}}</ref> In June 1987, they announced the full withdrawal of the PC/XT and the imminent discontinuation of the PC/AT. The last units of PC/AT (model 339) rolled off the assembly line in July.<ref name=atdiscontinued/> While the PC/XT received a directly compatible replacement in the form of the [[IBM PS/2 Model 30|PS/2 Model 30]], the AT did not. Users either had to forgo all their 16-bit ISA expansion cards and switch to the proprietary [[Micro Channel architecture]], or settle for a clone if they wanted to upgrade their machine while keeping their expansions. Eventually, in September 1988, IBM announced the [[IBM PS/2 Model 30 286|PS/2 Model 30 286]], which featured an Intel 80286 processor and 16-bit ISA expansion slots,<ref name=Reuters1988>{{cite news | agency=Reuters | date=September 14, 1988 | url=https://www.proquest.com/docview/389348570 | title=IBM Adding PS/2 Computer Compatible with AT Models | work=Sun-Sentinel | page=3D|id={{ProQuest|389348570}}}}</ref><ref name=Miller1988>{{cite journal | last=Miller | first=Michael W. | date=September 14, 1988 | url=https://www.proquest.com/docview/398059991 | title=IBM Introduces Low-end PC Aimed at Single Users | journal=The Wall Street Journal | publisher=Dow Jones & Company | page=1  |id={{ProQuest|398059991}}}}</ref> serving as the direct replacement for the AT for customers who wanted to buy a true IBM system.<ref name=Rosch1989>{{cite journal | last=Rosch | first=Winn L. | date=January 17, 1989 | url=https://books.google.com/books?id=C6VFJIbxX7MC&pg=PA267 | title=What's Old Is New | journal=PC Magazine | publisher=Ziff-Davis | volume=8 | issue=1 | pages=259–272 | via=Google Books}}</ref>
 ==Timeline==

IBM Personal Computer AT: Difference between revisions

Latest revision as of 01:20, 23 December 2025

Name

History

Features

Storage

Peripherals

Models

Power supply

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Clones

Reception

Successor

Timeline

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