One 8-bit and five 16-bit ISA slots on a motherboard
First Compaq logo, used until 1993
8-bit XT, 16-bit ISA, EISA (top to bottom)
Compaq Portable
8-bit XT: Adlib FM Sound card
Compaq Portable 386 BIOS
16-bit ISA: Madge 4/16 Mbps Token Ring NIC
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 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

4 related topics

Alpha

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

IBM PC compatible

IBM PC compatible computers are similar to the original IBM PC, XT, and AT that are able to use the same software and expansion cards.

IBM PC compatible computers are similar to the original IBM PC, XT, and AT that are able to use the same software and expansion cards.

The Compaq Portable was one of the first nearly 100% IBM-compatible PCs.
The original IBM PC (Model 5150) motivated the production of clones during the early 1980s.
The DEC Rainbow 100 runs MS-DOS but is not compatible with the IBM PC.
MS-DOS version 1.12 for Compaq Personal Computers
The PowerPak 286, an IBM PC compatible computer running AutoCAD under MS-DOS.

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.

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.

Three EISA slots

Extended Industry Standard Architecture

Bus standard for IBM PC compatible computers.

Bus standard for IBM PC compatible computers.

Three EISA slots
SCSI controller (Adaptec AHA-1740)
Fast SCSI RAID controller (DPT PM2022)
ELSA Winner 1000 Video card for ISA and EISA
200px

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

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
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.

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

First microcomputer released in the IBM PC model line and the basis for the IBM PC compatible de facto standard.

First microcomputer released in the IBM PC model line and the basis for the IBM PC compatible de facto standard.

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

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.