Editing Compaq Portable (section)

== Design ==
The Compaq Portable has basically the same hardware as an [[IBM PC]], with Compaq's [[BIOS]] instead of IBM's, transplanted into a luggable case specifically designed to fit as carry-on luggage on an airplane,.<ref name=oldcomputers/> (An engineer said that the Portable fits under an airplane seat if no one too heavy sat above it.){{r|wilcox}} All Portables shipped with 128&nbsp;KB of RAM and 1-2 double-sided double-density 360&nbsp;KB disk drives. Like the non-portable IBM PC, the Compaq Portable runs on power from an AC outlet only; it has no battery.

The machine has a hybrid of the [[IBM MDA]] and [[Color Graphics Adapter|CGA]] which supports the latter's graphics modes, but uses the former's high-quality character set in 80x25 text mode.{{r|dahmke198301}} (When [[Mitch Kapor]] saw the Portable use both standards while demonstrating [[Lotus 1-2-3]] to [[Sears Business Centers]], he stopped the presentation to explain his amazement at Compaq's achievement.<ref name="wilcox">{{Cite web |last=Wilcox |first=Joe |title=The Compaq Portable: The machine that forever altered the computer industry landscape |url=http://www.crn.com/crn/special/supplement/816/816p61_hof.jhtml |archive-url=http://web.archive.org/web/20100204231953/http://www.crn.com:80/crn/special/supplement/816/816p61_hof.jhtml |archive-date=2010-02-04 |access-date=2025-05-16 |website=ChannelWeb}}</ref>) When using the internal monochrome monitor the 9×14 font is used, and the 8×8 one when an external monitor is used (the user switches between internal and external monitors by pressing {{key press|Ctrl|Alt|>}}). With a larger external monitor, the graphics hardware is also used in the original [[Compaq Deskpro]] desktop computer.

Compaq used a "foam and foil" keyboard from Keytronics, with contact mylar pads that were also featured in the Tandy TRS-80, Apple Lisa 1 and 2, Compaq Deskpro 286 AT, some [[mainframe]] [[computer terminal|terminals]], [[Sun Microsystems|SUN]] Type 4, and some [[Wang Laboratories|Wang]] keyboards. The foam pads the keyboards used to make contact with the circuit board when pressed disintegrate over time, due to both the wear of normal use and natural wear. The CRT display also suffered from a low [[refresh rate]] and heavy [[Ghosting (television)|ghosting]].

{{Gallery
|title=Various views
|width=200
|height=200
|align=center
|File:Compaq portable-IMG 7218.jpg|Front of the suitcase, with connectors for parallel and CGA port 
|File:Compaq portable-IMG 7220.jpg|Rear of the suitcase, with AC power input
|File:Compaq portable-IMG 7221.jpg|Bottom of the suitcase with removable keyboard; stand is deployed
|File:Compaq portable-IMG 7222.jpg|Keyboard removed, computer ready for use
}}

=== Software ===
[[File:Compaq Portable and Wordperfect.JPG|thumb|Running WordPerfect 5.0]]
Compaq's efforts were possible because IBM had used mostly [[Commercial off-the-shelf|off-the-shelf]] parts for the PC and published full technical documentation for it, and because [[Microsoft]] had kept the right to license [[MS-DOS]] to other computer manufacturers. The only difficulty was the BIOS, because it contained IBM's copyrighted code. Compaq solved this problem by producing a [[clean room design|clean room]] workalike that performed all documented functions of the IBM PC BIOS, but was completely written from scratch.

Although numerous other companies soon also began selling PC compatibles, few matched Compaq's achievement of essentially-complete software compatibility with the IBM PC (typically reaching "[[PC compatible#Compatibility issues|95% compatibility]]" at best) until [[Phoenix Technologies]] and others began selling similarly reverse-engineered [[BIOS]]s on the open market.<ref name="alsop19940131">{{cite news | url=https://books.google.com/books?id=AzsEAAAAMBAJ&q=%22flight+simulator%22&pg=PT1 | title=A public Windows pane to make compatibility clearer | accessdate=February 28, 2011 | last=Alsop | first=Stewart | date=1994-01-31 | publisher=InfoWorld | pages=102}}</ref>

The first Portables used Compaq DOS 1.10,{{Citation needed|date=November 2019}} essentially identical to PC DOS 1.10 except for having a standalone [[BASIC]] that did not require the IBM PC's [[read-only memory|ROM]] Cassette BASIC, but this was superseded in a few months by DOS 2.00 which added hard disk support and other advanced features.

Aside from using DOS 1.x, the initial Portables are similar to the 16&nbsp;KB – 64&nbsp;KB models of the IBM PC in that the BIOS was limited to 544&nbsp;KB of RAM and did not support expansion ROMs, thus making them unable to use [[Enhanced Graphics Adapter|EGA]]/[[VGA]] cards, hard disks, or similar hardware. After DOS 2.x and the [[IBM XT]] came out, Compaq upgraded the BIOS. Although the Portable was not offered with a factory hard disk, users commonly installed them. Starting in 1984, Compaq began offering a hard disk-equipped version, the Portable Plus, which also featured a single half-height floppy drive. The hard disk offered would be 10 to 21 megabytes, although [[bad sector]]s often reduced the space available for use.

In 1985, Compaq introduced the Portable 286, but it was replaced by the more compact Portable II in a redesigned case within a few months. The Portable 286 featured a full-height hard disk, and the options of one half-height floppy drive, two half-height floppy drives, or a half-height floppy drive and a tape backup drive.