Editing Compaq Portable series (section)

== Design ==
The Compaq Portable has basically the same off-the-shelf hardware as an [[IBM PC]], transplanted into a luggable case (specifically designed to fit as carry-on luggage on an airplane), with Compaq's [[BIOS]] instead of IBM's.<ref name=oldcomputers/> All Portables shipped with 128k of RAM and 1-2 double-sided double-density 360 KB disk drives.

The machine uses a unique hybrid of the [[IBM MDA]] and [[IBM CGA|CGA]] which supports the latter's graphics modes but contains both cards' text fonts in ROM.{{r|dahmke198301}} In text modes, the 9x14 font is used on the internal monochrome monitor, and the 8x8 font is used on an external monitor. (The user switches between internal and external monitors by pressing {{key press|Ctrl|Alt|>}}.) The user can use both IBM video standards, for graphics capabilities and high-resolution text. The same graphics hardware is also used in the original [[Compaq Deskpro]] desktop computer.

The internal CRT monitor has a low refresh rate and exhibits heavy ghosting; this was not a Compaq choice but a consequence of replicating the IBM MDA design, which uses a 50 Hz refresh rate and a long-persistence P39 green phosphor CRT (in the [[IBM 5151]] video display). IBM chose this design to provide high vertical resolution&mdash;for sharp text&mdash;with low flicker for low eye strain over long (all-workday) periods of use.

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 terminals, SUN Type 4, and some 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 aging degradation.