The Compaq Portable was one of the first nearly 100% IBM-compatible PCs.
One 8-bit and five 16-bit ISA slots on a motherboard
The original IBM PC (Model 5150) motivated the production of clones during the early 1980s.
First Compaq logo, used until 1993
8-bit XT, 16-bit ISA, EISA (top to bottom)
The DEC Rainbow 100 runs MS-DOS but is not compatible with the IBM PC.
Compaq Portable
8-bit XT: Adlib FM Sound card
MS-DOS version 1.12 for Compaq Personal Computers
Compaq Portable 386 BIOS
16-bit ISA: Madge 4/16 Mbps Token Ring NIC
The PowerPak 286, an IBM PC compatible computer running AutoCAD under MS-DOS.
Aerial map of the Compaq headquarters, now the HP USA campus in unincorporated Harris County, Texas
16-bit ISA: Ethernet 10Base-5/2 NIC
Former Compaq headquarters, now the Hewlett-Packard United States campus
8-bit XT: US Robotics 56k Modem
Post merger logo for Compaq products.
An example of a HP Compaq.

Compaq produced some of the first IBM PC compatible computers, being the second company after Columbia Data Products to legally reverse engineer the IBM Personal Computer.

- Compaq

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.

- Industry Standard Architecture

Soon after in 1982, Compaq released the very successful Compaq Portable in 1982, also with a clean-room reverse-engineered BIOS, and also not challenged legally by IBM.

- IBM PC compatible

It was later re-named the Industry Standard Architecture (ISA) bus, after the Extended Industry Standard Architecture bus open standard for IBM PC compatibles was announced in September 1988 by a consortium of PC clone vendors, led by Compaq and called the Gang of Nine, as an alternative to IBM's proprietary Micro Channel architecture (MCA) introduced in its PS/2 series.

- IBM PC compatible

Compaq created the term "Industry Standard Architecture" (ISA) to replace "PC compatible".

- Industry Standard Architecture

Although Compaq had become successful by being 100 percent IBM-compatible, it decided to continue with the original AT bus—which it renamed ISA—instead of licensing IBM's MCA.

- Compaq
The Compaq Portable was one of the first nearly 100% IBM-compatible PCs.

3 related topics with Alpha

Overall

Three EISA slots

Extended Industry Standard Architecture

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Three EISA slots
SCSI controller (Adaptec AHA-1740)
Fast SCSI RAID controller (DPT PM2022)
ELSA Winner 1000 Video card for ISA and EISA
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The Extended Industry Standard Architecture (in practice almost always shortened to EISA and frequently pronounced "eee-suh") is a bus standard for IBM PC compatible computers.

In comparison with the AT bus, which the Gang of Nine retroactively renamed to the ISA bus to avoid infringing IBM's trademark on its PC/AT computer, EISA is extended to 32 bits and allows more than one CPU to share the bus.

Compaq Computer Corporation

IBM XGA-2 32-bit Graphics Card

Micro Channel architecture

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Proprietary 16- or 32-bit parallel computer bus introduced by IBM in 1987 which was used on PS/2 and other computers until the mid-1990s.

Proprietary 16- or 32-bit parallel computer bus introduced by IBM in 1987 which was used on PS/2 and other computers until the mid-1990s.

IBM XGA-2 32-bit Graphics Card
IBM XGA-2 32-bit Graphics Card
CHIPS P82C612 in a PLCC package
IBM 83X9648 16-bit Network Interface Card
Roland MPU-IMC; second revision with IRQ jumpers
ChipChat 16 with software-controlled IRQ selection

In IBM products, it superseded the ISA bus and was itself subsequently superseded by the PCI bus architecture.

The PC clone market did not want to pay royalties to IBM in order to use this new technology, and stayed largely with the 16-bit AT bus, (embraced and renamed as ISA to avoid IBM's "AT" trademark) and manual configuration, although the VESA Local Bus (VLB) was briefly popular for Intel '486 machines.

For servers the technical limitations of the old ISA were too great, and, in late 1988, the "Gang of Nine", led by Compaq, announced a rival high-performance bus - Extended Industry Standard Architecture (EISA).

IBM Personal Computer with keyboard and monitor

IBM Personal Computer

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IBM Personal Computer with keyboard and monitor
IBM Personal Computer with keyboard and monitor
Internal view of a PC compatible computer, showing components and layout.
Original IBM Personal Computer motherboard
IBM PC with MDA monitor
IBM Model F keyboard
IBM Personal Computer with IBM CGA monitor (model 5153), IBM PC keyboard, IBM 5152 printer and paper stand. (1988)
The back of a PC, showing the five expansion slots
PC DOS 3.30 running on an IBM PC
Digital Research CP/M-86 Version 1.0 for the IBM PC

The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first microcomputer released in the IBM PC model line and the basis for the IBM PC compatible de facto standard.

IBM referred to these as "I/O slots," but after the expansion of the PC clone industry they became retroactively known as the ISA bus.

Simple duplication of the IBM PC BIOS was a direct violation of copyright law, but soon into the PC's life the BIOS was reverse-engineered by companies like Compaq, Phoenix Software Associates, American Megatrends and Award, who either built their own computers that could run the same software and use the same expansion hardware as the PC, or sold their BIOS code to other manufacturers who wished to build their own machines.