Also known as | IBM XT, PC/XT, XT |
---|---|
Manufacturer | IBM |
Type | Personal computer |
Release date | March 8, 1983 |
Discontinued | April 1987 |
Operating system | IBM BASIC / PC DOS 2.0-3.20 / PC/IX / SCO Xenix |
CPU | Intel 8088 @ 4.77 MHz |
Memory | 128 KB – 640 KB |
Storage | 10–20 MB hard drive |
Graphics | MDA, CGA |
Sound | PC speaker 1-channel square-wave/1-bit digital (PWM-capable) |
Power | 120/240 VAC |
Dimensions | W: 19.5 in (50 cm) H: 5.5 in (14 cm) D: 16 in (41 cm) |
Mass | 32 lb (15 kg) |
Predecessor | IBM Personal Computer |
Successor |
|
Related | List of IBM Personal Computer models |
The IBM Personal Computer XT (model 5160, often shortened to PC/XT) is the second computer in the IBM Personal Computer line, released on March 8, 1983. [1] Except for the addition of a built-in hard drive and extra expansion slots, it is very similar to the original IBM PC model 5150 from 1981.
IBM did not specify an expanded form of "XT" on the machine, press releases, brochures or documentation, but some publications expanded the term as "eXtended Technology" or just "eXTended". [2]
The XT was regarded as an incremental improvement over the PC and a disappointment compared to the next-generation successor that some had anticipated. Compared to the original IBM PC, the XT has the following major differences: [3]
Otherwise the specifications are identical to the original PC.
The number of expansion slots in the original IBM PC was a limiting factor for the product, since essential components (such as the video controller, disk controller and printer interface) each came as separate expansion cards and could quickly fill up all five available slots, requiring the user to swap cards in and out as tasks demanded. [5] Some PC clones addressed this problem by integrating components into the motherboard to free up slots, [6] while peripheral manufacturers produced products which integrated multiple functions into one card. [7] [8]
The XT addressed the problem by adding three extra expansion slots for a total of eight. While the slots themselves are identical to those in the original PC, the amount of physical space in the chassis differs, so two of the new slots (located behind the hard drive) cannot accept full-length cards. In addition, the spacing of the slots is narrower than in the original PC, making it impossible to install some multi-board cards. [3] [8]
The 5161 is an expansion chassis using an identical case and power supply to the XT, but instead of a system board, provides a backplane with eight card slots. It connects to the main system unit using an Extender Card in the system unit and a Receiver Card in the Expansion Unit, connected by a custom cable. [3] The 5161 shipped with a 10 MB hard drive, and had room for a second one. [8]
The Expansion Unit can also contain extra memory, but the Extender card inserts wait states for memory in the Expansion Unit, so it may be preferable to install memory into the main system unit.
The 5161 can be connected to either an XT or to the earlier 5150 (the original IBM PC). [9]
PC DOS 2.0 offers a 9-sector floppy disk format, providing 180K/360K (single- vs. dual-sided) capacity per disk, compared to the 160K/320K provided by the 8-sector format of previous releases. [3]
The XT was not offered in a floppy-only model for its first two years on the market, although the standard ribbon cable with two floppy connectors was still included. At that time, in order to get a second floppy drive, the user had to purchase the 5161 expansion chassis. [8]
Like the original PC, the XT came with IBM BASIC in ROM. The XT BIOS also displays a memory count during the POST, unlike the original PC.
The XT has a desktop case similar to that of the IBM PC. It weighs 32 pounds (15 kg) and is approximately 19.5 inches (50 cm) wide by 16 inches (41 cm) deep by 5.5 inches (14 cm) high.
Similarly to the original IBM PC, the XT main board included a socket for the Intel 8087 floating point arithmetic coprocessor. This optional chip, when installed, greatly accelerated arithmetic for such applications as computer aided design or other software that required large amounts of arithmetical calculations. Only software that was especially written to take advantage of the coprocessor would show a significant speedup. [10]
The power supply is 130 watts, an upgrade from the original PC. Those sold in the US were configured for 120 V AC only and could not be used with 240 V mains supplies. [10] XTs with 240 V-compatible power supplies were later sold in international markets. Both were rated at 130 watts. [11]
IBM made several submodels of the XT.
The 3270 PC, a variant of the XT featuring 3270 terminal emulation, was released in October 1983.
Submodel 068 and 078, released in 1985, offered dual-floppy configurations without a hard drive as well, and the new Enhanced Graphics Adapter and Professional Graphics Adapter became available as video card options. [10]
In 1986, the 256–640 KB motherboard models were launched, which switched to half-height drives.
Submodels 268, 278 and 089 came with 101-key keyboards (essentially the IBM Model M, but in a modified variant that used the XT's keyboard protocol and lacked LEDs).
Submodels 267, 277 and 088 had the original keyboard, but 3.5" floppy drives became available and 20MB Seagate ST-225 hard disks in 5.25" half-height size replaced the full-height 10 MB drives.
Submodel 788 was the only XT sold with the Color Graphics Adapter as a standard feature. [11]
Submodels 568, 588, and 589 were used as basis for the XT/370; they had an additional (co-)processor board that could execute System/370 instructions. [11] An XT-based machine with a Series/1 co-processor board existed as well, but it had its own System Unit number, the IBM 4950. [12]
In 1986, the XT 286 (model 5162) was released with a 6 MHz Intel 80286 processor. Despite being marketed as a lower-tier model than the IBM AT, this system runs many applications faster than the ATs of the time with 6 MHz 286 processors, since it has zero-wait state RAM. [10] : 95
It shipped with 640 KB RAM standard, an AT-style 1.2 MB high-density diskette drive and a 20 MB hard disk. [13] [14] Despite these features, reviews rated it as a poor market value. [15]
The XT 286 uses a 157-watt power supply, which can internally switch between 115 or 230 V AC operation. [13]
Both the original XT and the XT/286 was discontinued in late 1987 after the launch of the IBM Personal System/2 (PS/2) line. The 8086-powered IBM PS/2 Model 30 served as the direct replacement for the XT in that PS/2 line. Unlike higher-end entries in the PS/2 line, which feature the Micro Channel expansion bus, the Model 30 contains 8-bit ISA bus slots, exactly like the XT.
Type | IBM P/N | Date announced | Date withdrawn | Bus | No. of slots | No. of bays | Processor | Clock speed (MHz) | Stock onboard RAM (KB) | Maximum onboard RAM (KB) | FDD | HDD | Notes | Ref(s). |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
XT | 5160-087 | March 1983 | June 1984 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 128 KB | 640 KB | 360 KB | 10 MB | [16] : 236 [17] [18] : 1068 | |
XT | 5160-086 | June 1984 | June 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 256 KB | 640 KB | 360 KB | 10 MB | [16] : 236 [19] [20] [21] | |
XT | 5160-068 | April 1985 | June 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 256 KB | 640 KB | 360 KB | none | [16] : 236 [18] : 1068 [22] [20] [21] | |
XT | 5160-078 | April 1985 | June 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 256 KB | 640 KB | two 360 KB | none | [16] : 236 [18] : 1068 [22] [20] [21] | |
XT | 5160-088 | April 1986 | June 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 512 KB | 640 KB | 360 KB | 20 MB | Shipped with original IBM PC "Model F" keyboard | [16] : 236 [23] [20] [21] |
XT | 5160-089 | April 1986 | June 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 512 KB | 640 KB | 360 KB | 20 MB | Shipped with Enhanced Keyboard | [16] : 236 [23] [20] [21] |
XT | 5160-267 | April 1986 | June 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 256 KB | 640 KB | 360 KB | none | Shipped with original IBM PC "Model F" keyboard | [16] : 236 [23] [20] [21] |
XT | 5160-268 | April 1986 | June 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 256 KB | 640 KB | 360 KB | none | Shipped with Enhanced Keyboard | [16] : 236 [23] |
XT | 5160-277 | April 1986 | June 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 256 KB | 640 KB | two 360 KB | none | Shipped with original IBM PC "Model F" keyboard | [23] |
XT | 5160-278 | April 1986 | June 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 256 KB | 640 KB | two 360 KB | none | Shipped with Enhanced Keyboard | [16] : 236 [23] |
3270 PC | 5271-000 | Unknown | July 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 256 KB | 640 KB | 360 KB | none | Without printer adapter, fixed disk adapter, and keyboard | [24] [25] |
3270 PC | 5271-002 | October 1983 | July 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 256 KB | 640 KB | 360 KB | none | Without printer adapter and fixed disk adapter | [16] : 49 [19] [26] : 10 [25] |
3270 PC | 5271-004 | October 1983 | July 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 320 KB | 640 KB | 360 KB | none | Without fixed disk adapter; stock onboard RAM increased to 384 KB in June 1984 | [16] : 49 [19] [26] : 10 [25] |
3270 PC | 5271-006 | October 1983 | July 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 320 KB | 640 KB | 360 KB | 10 MB | With fixed disk adapter; stock onboard RAM increased to 384 KB in June 1984 | [16] : 49 [19] [26] : 10 [25] |
XT/370 | 5160-568 | October 1984 | April 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 256 KB | 640 KB | 360 KB | none | [16] : 236 [26] [27] | |
XT/370 | 5160-588 | October 1984 | April 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 256 KB | 640 KB | 360 KB | 10 MB | [16] : 236 [26] [27] | |
XT/370 | 5160-589 | October 1984 | April 1987 | ISA, 8-bit | 8 | 2 | Intel 8088 | 4.77 | 256 KB | 640 KB | 360 KB | 10 MB | [16] : 236 [27] | |
XT Model 286 | 5162-286 | September 1986 | October 1987 | ISA, 16-bit | 8 | 2 | Intel 80286 | 6 | 640 KB | 640 KB | 1.2 MB | 20 MB | [16] : 48 [28] [21] |
The XT was well received, although PC DOS 2.0 was regarded as a greater improvement than any of the hardware changes, and by the end of 1983 IBM was selling every unit they made. [29]
The Compaq Portable also came out in March 1983, [30] and would prove a popular competitor. Sometimes called the "first PC clone" [31] and first "legal clone", [32] that distinction may go to another offering: Columbia Data Products' MPC 1600 "Multi Personal Computer", in June 1982. [33] [34] Other "clones" included the Seequa Chameleon, [35] [36] [37] the Hyperion, [38] Eagle Computer's Eagle 1600 that September [39] and the Corona PC. [40] The latter two companies were sued by IBM and settled out of court, agreeing to re-implement their BIOS in a way that did not violate IBM's copyrights. [41] AT&T, who owned a 25% share of Olivetti, released the AT&T PC 6300 in June 1984, which was a re-branded version of the Olivetti M24. The PC 6300 offered the 16-bit 8086 clocked at a faster 8 MHz speed that was technically superior to IBM's PC XT.
Timeline of the IBM Personal Computer |
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Asterisk (*) denotes a model released in Japan only |
Industry Standard Architecture (ISA) is the 16-bit internal bus of IBM PC/AT and similar computers based on the Intel 80286 and its immediate successors during the 1980s. The bus was (largely) backward compatible with the 8-bit bus of the 8088-based IBM PC, including the IBM PC/XT as well as IBM PC compatibles.
The IBM Personal Computer is the first microcomputer released in the IBM PC model line and the basis for the IBM PC compatible de facto standard. Released on August 12, 1981, it was created by a team of engineers and designers at International Business Machines (IBM), directed by William C. Lowe and Philip Don Estridge in Boca Raton, Florida.
The Tandy 1000 is the first in a line of IBM PC compatible home computer systems produced by the Tandy Corporation for sale in its Radio Shack and Radio Shack Computer Center chains of stores. Introduced in 1984, the product line was aimed at providing affordable but capable systems for home computing or education, with some of its Tandy specific features like graphics, sound and joystick port making it more appealing for home use.
The Personal System/2 or PS/2 is IBM's second generation of personal computers. Released in 1987, it officially replaced the IBM PC, XT, AT, and PC Convertible in IBM's lineup. Many of the PS/2's innovations, such as the 16550 UART, 1440 KB 3.5-inch floppy disk format, 72-pin SIMMs, PS/2 port, and VGA video standard, went on to become standards in the broader PC market.
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The Compaq Portable is an early portable computer which was one of the first IBM PC compatible systems. It was Compaq Computer Corporation's first product, to be followed by others in the Compaq Portable series and later Compaq Deskpro series. It was not simply an 8088-CPU computer that ran a Microsoft DOS as a PC "work-alike", but contained a reverse-engineered BIOS, and a version of MS-DOS that was so similar to IBM's PC DOS that it ran nearly all its application software. The computer was also an early variation on the idea of an "all-in-one".
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has generic name (help)IBM's recent announcement that it will formally discontinue its PC XT line and eventually phase out its PC AT came as no surprise to many corporate users. [...] William Lowe, president of IBM's Entry Systems Division in Boca Raton, Fla., told Wall Street analysts on June 30 that the only remaining XT, the XT 286, will be discontinued within three months and that IBM is working with dealers and large accounts to determine how many more ATs it will make to fill orders.
The new floppy disk-based versions of the PC XT basically just strips the 10MB hard disk from the earlier unit. The machines come with base memory of 256KB and are available in either single or dual 360 KB diskette versions. A single diskette unit with keyboard and 256 KB of main memory is priced at $2,270, while the dual diskette version is priced at $2,570. A fully configured PC XT with 256 KB of RAM, a 360 KB diskette, keyboard, monochrome monitor and adapter, and operating system comes in at about $2,860.
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