The History Of The IBM Personal Computer

While Apple introduced the Apple II ahead of the IBM PC, it was an IBM product under the visionary leadership of Don Estridge that ignited the era of personal computing. There were a number of unique aspects of the IBM PC that made it different from previous IBM products. In designing the IBM PC, the team at IBM elected to use off-the-shelf parts rather than the usual IBM-sourced components. In another unconventional decision, they publicly released the basic hardware specification to encourage other companies to manufacture and sell IBM compatible boards. Last of all they decided not to exclusively provide the software applications for the product, but instead to encourage third-parties to develop software for the PC and license it directly to customers. Except for a critical piece of code called BIOS, the PC truly was an open hardware architecture. Every major and minor component, enclosures, motherboards, disk, memory, bus, even the CPU would eventually be easily second-sourced.

Spawned the PC Era

The consequences of these IBM decisions not only spawned the PC era, but also led to the creation of a new and highly profitable PC software segment. To help complementary hardware designers and software publishers create expansion hardware and software applications, IBM published the essential BIOS code for the PC. The BIOS remained copyrighted by IBM since they intended to use it to prevent unlicensed cloning of the IBM PC. Unfortunately for IBM the BIOS was soon reverse engineered by Compaq and others using a “clean room” process that avoided legal liability for copyright infringement. This gave low-cost makers of PC clones the last technology piece they needed to deliver inexpensive PCs. The resulting explosive growth of PC clone sales and adoption ultimately changed all aspects of computing, creating a wealth of new companies like Microsoft, Intel, Compaq, Dell, and subsequently drove acceptance of the PC architecture into more demanding server applications at the enterprise level.

Over a Billion PCs Sold

Within 25 years over a billion PCs were sold. Still the leading computing architecture, the second billionth PC was shipped sometime in 2008. How could such enormous consequences arise from a few relatively modest engineering decisions? The answer seems simple. Open architectures are vastly more efficient to extend, allowing many more individuals and companies to contribute and participate in accelerating the design, application, low-cost manufacturing and distribution of a product. IBM didn’t intend to create an open platform with the IBM PC. It just didn’t foresee that the BIOS code would be reverse engineered. In an attempt to regain control, IBM created a new proprietary system bus called the MCA and licensed it for hundreds of dollars. While this approach would prevent others from cloning new IBM PCs without a license, the MCA bus was adopted by virtually no one outside of IBM. Instead, the clone makers created their own standard ISA bus which was soon followed by an even faster EISA bus.

Peripheral Component Interface

A similarly important milestone in the history of the PC was the introduction by Intel of the Peripheral Component Interface or “PCI” standard. Intel realized they should create a standard bus and support it with low-cost Intel chips. Intel designed the PCI bus to be fast, inexpensive to build, and royalty-free. ¬†With Intel behind it, the jockeying between IBM and the clone makers about board compatibility ended. The enormously successful PCI specification and its successors since 1992 are still the dominant local bus system within PCs and servers. Today PCI versions continue to receive wide support from all PC manufacturers globally. The PCI bus from Intel was wildly successful in simplifying integration, further driving down the PC system costs, and vastly improving PC reliability for all consumers and businesses.

John Koenig is the founder of Compute Media and designer of Patent Studio. You can follow him on Twitter @johnkoenig.

Photo Credit: A. Disc