Compaq Portable series

Compaq Portable series
Company type	Product line
Industry	Computer hardware
Founder	Compaq Computer Corporation
Products	Portable computers

Compaq initially launched its product line with portable computers known as the Compaq Portable series. These early "luggable" machines measured approximately deep, tall, and wide. The series progressed from early models like the Compaq Portable and Compaq Portable II, which used CRT displays, to later iterations such as the Compaq Portable III and Compaq Portable 386, which incorporated flat amber plasma screens. These portable units included internal hard drives mounted with shock absorption, 5¼" floppy disk drives, batteries, and dual-ISA expansion bays. The Compaq Portable 486 advanced the line by introducing monochrome and color LCD panels powered by batteries.

Models in the series

Compaq Portable – Compaq's inaugural computer and their first fully IBM PC compatible system
- Compaq Portable Plus – featured an integrated hard drive
- Compaq Portable 286 – equivalent to the PC AT housed in the original case; equipped with a 6/8-MHz 286 processor and a 20-MB hard disk
Compaq Portable II – a more compact, lighter iteration of the Portable 286; offered at a lower price point but with restricted upgrade options and a slower hard drive
Compaq Portable III
- Compaq Portable 386
Compaq Portable 486 and Compaq Portable 486c

The Compaq Portable marked a breakthrough as one of the earliest portable IBM PC compatible computers and represented Compaq Computer Corporation’s debut product, setting the stage for the subsequent Compaq Deskpro lineup.

Launch and Commercial Success

Unveiled in November 1982 and released in March 1983 with a starting price of , the Compaq Portable featured a foldable design resembling a sewing machine case. It achieved sales of 53,000 units within its first twelve months, generating revenue of , an unprecedented figure for an American company at that time. Earnings grew to in its second year and reached in year three, establishing new standards within the industry.

As one of the first all-in-one portable IBM PC compatible systems, it arrived shortly after CP/M-based rivals such as the Osborne 1 and Kaypro II but set itself apart by offering complete IBM PC compatibility. Its design was influenced by Xerox PARC’s NoteTaker prototype. Competing portable "work-alike" models like the Seequa Chameleon and Corona PPC-400 experienced limited commercial success.

In response, IBM introduced the IBM Portable PC to directly challenge Compaq’s innovative product.

Technical Design

The Compaq Portable incorporated essentially identical off-the-shelf components found in an IBM PC, enclosed within a luggable chassis designed to fit airplane carry-on dimensions. It replaced IBM’s BIOS with Compaq’s proprietary firmware. Each unit came standard with 128k RAM alongside one or two double-sided, double-density floppy drives holding 360 KB each.

Its video system combined elements of both the IBM MDA and CGA standards, enabling CGA graphics support while embedding text fonts from both cards in ROM. In text mode, it utilized a 9x14 font on its internal monochrome screen and an 8x8 font on external monitors, selectable via . This hybrid video hardware was also implemented in the original Compaq Deskpro desktop computers.

The internal CRT display operated at a low refresh rate that caused ghosting effects; this was due to mimicking IBM MDA’s standard of a 50 Hz refresh rate intended to produce crisp text and minimize eye fatigue during extended use.

For input, Compaq employed a “foam and foil” keyboard manufactured by Keytronics, which used contact mylar pads similar to those found in devices like the Tandy TRS-80 and Apple Lisa. These foam pads were prone to deterioration over time because of wear and aging.

Software

Compaq's achievement was largely due to IBM's reliance on widely available components and openly shared technical specifications, combined with Microsoft's strategy of licensing MS-DOS to various hardware manufacturers. The primary obstacle involved duplicating IBM’s BIOS without violating copyright laws; Compaq overcame this by employing a clean room methodology that recreated the BIOS functionality entirely from the ground up.

Although numerous competitors produced IBM PC-compatible machines, few attained the level of software compatibility that Compaq did, which was nearly complete, while others typically achieved around 95%. Later on, companies such as Phoenix Technologies began marketing BIOS versions developed through reverse engineering.

The earliest Portables operated MS-DOS in a manner almost identical to PC DOS 1.10 but featured a standalone BASIC interpreter independent from IBM’s ROM Cassette BASIC. This was shortly superseded by MS-DOS 2.00, which introduced support for hard drives and additional enhancements. Initial BIOS iterations restricted RAM to 544K and did not support expansion ROMs, limiting compatibility with EGA/VGA graphics adapters and hard disk drives. Following the release of DOS 2.x and the IBM XT, Compaq updated its BIOS accordingly.

While factory-installed hard drives were not initially available, users frequently installed them later. Beginning in 1984, Compaq released the Portable Plus model offering optional 10 or 21 MB hard drives, though actual usable space was often diminished due to defective sectors.

Reception

BYTE lauded the Compaq Portable prototype for its portability, affordability, and robust compatibility with IBM PC software. Evaluations demonstrated successful operation of most programs, including IBM PC DOS, CP/M-86, WordStar, and SuperCalc. Similarly, PC Magazine commended its software compatibility, sturdy build quality, and clear display, recommending it for users requiring IBM PC applications without purchasing an IBM-branded machine.

Later Models

The Compaq Portable Plus upgraded one of its floppy drives to a hard drive and featured distinctive gold-colored logos, capitalizing on a niche created by custom modifications from retailers. In 1985, Compaq introduced the Portable 286 model, which was quickly succeeded by the more compact Portable II featuring a redesigned chassis. The Portable 286 represented Compaq’s take on the PC AT, equipped with a 286 processor and a hard drive, available with various floppy disk and tape backup options. In contrast, the Portable II was smaller, lighter, less costly but offered fewer upgrade possibilities and included a slower hard disk.

Launched in 1987, the Compaq Portable III was an AT-compatible system marketed as significantly reduced in size and weight compared to earlier portable x86 computers. The base Model 1 was priced at , including an Intel 80286 CPU, RAM, a floppy drive, and an amber gas-plasma display. Higher-tier variants featured larger storage: Model 20 came with at , while Model 40 included at . An optional ISA expansion unit accommodated two full-length 16-bit add-in cards for . These models required mains electricity and did not support battery operation.

Subsequent models in this lineup encompassed the Compaq Portable III, Portable 386, Portable 486, and Portable 486c.