IBM Personal Computer XT

Short description: Personal computer model released in 1983

IBM Personal Computer XT

Also known as| IBM XT, PC/XT, XT
Manufacturer| IBM
Type| Personal computer
Release date| March 8, 1983; 43 years ago (1983-03-08)
Discontinued| April 1987 (1987-04)
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|

* IBM Personal Computer AT (next model)
* IBM PS/2 Model 30 (direct replacement)

Related articles| 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.

## Contents

* 1 Name
* 2 Features
* 2.1 Expansion slots
* 2.2 Expansion unit
* 2.3 Other features
* 3 Revisions and variants
* 3.1 XT 286
* 3.2 Comparison table
* 4 Reception
* 5 Timeline
* 6 See also
* 7 References
* 8 External links

## Name

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]

## Features

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]

* The number of expansion slots was increased from five to eight
* Base RAM was increased to at least 128 KB
* 2x32KB ROM ICs replace the previous 5x8KB ROM ICs
* A 10 MB hard drive was included on most sub-models, with a disk controller featuring Xebec ICs[4]: 111
* PC DOS 2.0 was included
* The 5-pin DIN for the cassette interface was removed

Otherwise the specifications are identical to the original PC.

### Expansion slots

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]

### Expansion unit

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]

### Other features

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]

## Revisions and variants

IBM PC/XT 5160 dual floppy drives with 5153 Color Monitor

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]

### XT 286

XT 286 badge

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.

### Comparison table

Template:Sort-under

IBM Personal Computer XT models  Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | Date announced  | Date withdrawn  | Bus  | Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | Processor  | Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | FDD | HDD | Notes  | Ref(s).

|
|
|
|
|
|
|
|
|
|
|
|
|
|

Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | March 1983 | June 1984 | ISA,
8-bit  | 8  | 2  | Intel 8088 | 4.77  | 128 KB  | 640 KB  | 360 KB  | 10 MB  |  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | June 1984 | June 1987 | ISA,
8-bit  | 8  | 2  | Intel 8088 | 4.77  | 256 KB  | 640 KB  | 360 KB  | 10 MB  |  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | April 1985 | June 1987 | ISA,
8-bit  | 8  | 2  | Intel 8088 | 4.77  | 256 KB  | 640 KB  | 360 KB  | none  |  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | April 1985 | June 1987 | ISA,
8-bit  | 8  | 2  | Intel 8088 | 4.77  | 256 KB  | 640 KB  | two 360 KB  | none  |  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | 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  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | 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  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | 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  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | April 1986 | June 1987 | ISA,
8-bit  | 8  | 2  | Intel 8088 | 4.77  | 256 KB  | 640 KB  | 360 KB  | none  | Shipped with Enhanced Keyboard  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | 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  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | 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  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | 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  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | 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  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | 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  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | 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  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | October 1984 | April 1987 | ISA,
8-bit  | 8  | 2  | Intel 8088 | 4.77  | 256 KB  | 640 KB  | 360 KB  | none  |  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | October 1984 | April 1987 | ISA,
8-bit  | 8  | 2  | Intel 8088 | 4.77  | 256 KB  | 640 KB  | 360 KB  | 10 MB  |  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | October 1984 | April 1987 | ISA,
8-bit  | 8  | 2  | Intel 8088 | 4.77  | 256 KB  | 640 KB  | 360 KB  | 10 MB  |  | Template:Grid list
Script error: No such module "Vertical header". | Script error: No such module "Vertical header". | September 1986 | October 1987 | ISA,
16-bit  | 8  | 2  | Intel 80286 | 6  | 640 KB  | 640 KB  | 1.2 MB  | 20 MB  |

## Reception

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.[16] By 1985 the IBM PC AT made the XT obsolete for most customers.[17]

## Timeline

Template:Timeline of the IBM Personal Computer

## See also

* Amiga Sidecar
* PC-based IBM-compatible mainframes

## References

1. ↑ Enterprise, I. D. G. (August 11, 1986) (in en). Computerworld. IDG Enterprise. https://books.google.com/books?id=r6bSpuaCsE4C&q=IBM PC XT march 1983&pg=PA8.
2. ↑ Upgrading and Repairing PCs, 10th Edition. 1998. pp. 1115. http://ptgmedia.pearsoncmg.com/imprint_downloads/informit/que/upgrading/fourteenth_edition/DVD/PCs10th.pdf.
3. ↑ 3.0 3.1 3.2 3.3 "IBM Unveils Top-of-the-Line Personal Computer". Byte 8 (5): 520. May 1983. https://archive.org/details/byte-magazine-1983-05.
4. ↑ Barkow, Tim (October 1996). "The Bottom Feeders". Wired (Wired Ventures) 4 (10): 110–127. Archived from the original on November 12, 2015. https://web.archive.org/web/20151112091504/https://www.wired.com/1996/10/es-intaglio/.
5. ↑ Dievendorff, Dick (1981). IBM Personal Computer Questions and Answers. IBM. pp. 9–10. http://bitsavers.trailing-edge.com/pdf/ibm/pc/pc/.
6. ↑ Freeze, Ken (December 16, 1985). "Leading Edge: Superior Value In IBM-PC Clone Market Contest". InfoWorld: pp. 43. https://books.google.com/books?id=cC8EAAAAMBAJ&pg=PA43.
7. ↑ (in en) InfoWorld. InfoWorld Media Group, Inc.. November 14, 1983. https://books.google.com/books?id=wS8EAAAAMBAJ&q="Multifunction+Cards+for+IBM+PCs"&pg=PA76.
8. ↑ 8.0 8.1 8.2 8.3 "Inside the IBM PC". Byte 8 (11). November 1983. https://archive.org/details/byte-magazine-1983-11.
9. ↑ Personal Computer Family Service Information Manual (January 1989), IBM document SA38-0037-00, pages 7-1 to 7-3
10. ↑ 10.0 10.1 10.2 10.3 Mueller, Scott (1992). Upgrading and Repairing PCs (2nd ed.). Que Books. pp. 59–79. ISBN 0-88022-856-3.
11. ↑ 11.0 11.1 11.2 Personal Computer Family Service Information Manual (January 1989), IBM document SA38-0037-00, page 6-2
12. ↑ Personal Computer Family Service Information Manual (January 1989), IBM document SA38-0037-00, page 14-1
13. ↑ 13.0 13.1 Personal Computer Family Service Information Manual (January 1989), IBM document SA38-0037-00, pages 8-1 to 8-2
14. ↑ "The AT Clone from IBM", PC Magazine, January 13, 1987
15. ↑ InfoWorld. InfoWorld Media Group, Inc.. March 23, 1987. pp. 49. https://archive.org/details/bub_gb_yjAEAAAAMBAJ.
16. ↑ Archer, Rowland Jr. (November 1983). "The IBM PC XT and DOS 2.00". BYTE: pp. 294–304. https://archive.org/stream/byte-magazine-1983-11/1983_11_BYTE_08-11_Inside_the_IBM_PC#page/n301/mode/2up.
17. ↑ Pournelle, Jerry (January 1985). "The Fast Lane". BYTE: 363. https://archive.org/details/BYTE_Vol_10-01_1985-01_Through_The_Hourglass/page/363/mode/1up?view=theater. Retrieved 2024-10-04.

Notes

* IBM (1983). Personal Computer Hardware Reference Library: Guide to Operations, Personal Computer XT. IBM Part Number 6936831.

## External links

* IBM 5160 information at www.minuszerodegrees.net

Photo galleries:

* XT with 256 KB on system board
* XT 286

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*[FDD]: Floppy disk drive
*[HDD]: Hard disk drive