IBM and Apple Agree to Make Compatible Computers Summary

  • Last updated on November 10, 2022

After years of rivalry, IBM and Apple agreed to work together to create a new processor and a common hardware reference platform that would enable their computers to use the same software.

Summary of Event

Almost from the beginning, incompatible hardware and software had been the bane of the microcomputer industry. In its early days, there were dozens of companies, each with its own proprietary architecture. Changing computers often required one to laboriously retype all of one’s existing data. The introduction of the International Business Machines (IBM) personal computer (PC) in 1981 and the subsequent development of IBM compatibles, or “clones,” created a de facto standard throughout much of the computer industry. However, when Apple introduced the Macintosh in 1984, it chose to develop a completely different standard. Computers;compatibility Personal computers;compatibility IBM Apple Computer AIM alliance [kw]IBM and Apple Agree to Make Compatible Computers (July 3, 1991) [kw]Apple Agree to Make Compatible Computers, IBM and (July 3, 1991) [kw]Computers, IBM and Apple Agree to Make Compatible (July 3, 1991) Computers;compatibility Personal computers;compatibility IBM Apple Computer AIM alliance [g]North America;July 3, 1991: IBM and Apple Agree to Make Compatible Computers[08140] [g]United States;July 3, 1991: IBM and Apple Agree to Make Compatible Computers[08140] [c]Computers and computer science;July 3, 1991: IBM and Apple Agree to Make Compatible Computers[08140] [c]Trade and commerce;July 3, 1991: IBM and Apple Agree to Make Compatible Computers[08140] [c]Business and labor;July 3, 1991: IBM and Apple Agree to Make Compatible Computers[08140] Sculley, John Akers, John

By the 1990’s, the field had settled down to a rivalry between the Windows-based descendants of the IBM PC on one side and the Apple Macintosh on the other. However, IBM itself was rapidly losing market share in the microcomputer business, particularly to such firms as Compaq, Dell, and Gateway 2000. Thus IBM became increasingly interested in the possibility of a joint venture with Apple that would eliminate the seemingly unbridgeable gap between the two parts of the microcomputer world.

The idea was to create a new hardware platform based on a new microprocessor architecture and an advanced new operating system (OS) that would take advantage of the new chip’s particular strengths. All microprocessors Microprocessors up to that time were based on the complex instruction set computing (CISC) paradigm. However, Apple and IBM engineers were becoming increasingly convinced that CISC was ultimately a dead-end technology, and the future lay with a new theory known as RISC, or reduced instruction set computing. While a CISC microprocessor would have a large number of instructions, one for each possible task it might be asked to perform, a RISC microprocessor would be based on a few basic instructions that could be put together to build the equivalents of the specialized instructions of a CISC chip.

Because each instruction in a RISC chip has the same number of steps, it would also make the transition to a superscalar architecture easier. With a superscalar architecture, the processor has more than one data pipeline and is able to process more than one instruction during each clock cycle. If instructions require a number of steps to complete, it would be more difficult to keep the data pipelines synchronized. Periods in which one side was waiting for the other to finish an instruction represented processor power wasted. By contrast, the basic “building block” instructions of a RISC chip would always stay neatly in step with one another.

Along with this revolutionary new microprocessor design, IBM and Apple set forth ideas for the computers that would run them. The Common Hardware Reference Platform Common Hardware Reference Platform (CHRP) would be a standard architecture that would ensure that hardware worked in predictable ways and programmers would no longer have to rewrite their software completely with every change of basic hardware.

In order to realize these visions, Apple and IBM brought chip manufacturer Motorola Motorola on board, forming an organization called the AIM alliance. Motorola had been having trouble with the 88000 chip, the RISC-based successor to the old standby 68000 series of chips, which had been the brains of Apple computers to date. Thus Motorola gained access to IBM’s established POWER (Performance Optimization With Enhanced RISC) architecture, which had proven its worth in mainframes. Apple and IBM created two joint-venture companies, Taligent Taligent and Kaleida, Kaleida to create a new operating system and a powerful new object-oriented scripting language for developers. Both were intended to concentrate on fully utilizing the potential of this powerful new platform.


The long-term success of the AIM alliance was mixed. On one hand, the PowerPC chip became the basis for all of Apple’s computers for more than a decade, giving them the name of Power Macintosh. On the other hand, most of the other initiatives faced various problems.

IBM designed a new line of PowerPC-based computers, but problems getting an operating system that would run on them delayed its release. Originally they were planned to run Windows, but Microsoft failed to roll out a compatible version of its popular OS in time. IBM then fell back on its own OS/2 operating system, but rewriting it to work on the PowerPC chip consumed valuable time. By the time IBM’s programmers had the new version of OS/2 ready, the critical moment had already passed for the hardware, and only a few machines were ever sold. IBM ended up returning to the Intel fold and ultimately sold its microcomputer division to an Asian firm, Lenovo, in order to concentrate on its real bread and butter, mainframe computers such as the RS/6000 and its descendants.

Apple got around the operating system bottleneck by rewriting its existing System 7 to run on the PowerPC chip and by creating a 68K emulator to handle a few pieces of seldom-used code. However, Apple’s efforts to create a next-generation operating system became sidetracked into a multiplicity of approaches, and both OS 8 and OS 9 proved to be little more than updates of an operating system that dated back to the early days of the Macintosh. Finally, in danger of failing altogether, Apple brought back cofounder Steve Jobs Jobs, Steve and thus gained access to his powerful NEXTSTEP, a UNIX-based operating system that would become the basis of OS X.

The much-vaunted CHRP, later renamed PReP(PowerPC Reference Platform), ultimately went out with a whimper. Although a few machines based on it were shipped in the late 1990’s and it attained some currency among users of various flavors of UNIX, there simply was not enough advantage to the CHRP/PReP hardware over comparable Intel-based machines to allow them to compete. The BeBox, a machine designed to run the innovative BeOS, incorporated PReP hardware but was not completely compatible with the design. The machine never gained enough market share to be more than a curiosity. (However, before Jobs brought NEXTSTEP to Apple, there were some negotiations toward buying or licensing BeOS as the foundation of a replacement for the old Macintosh operating system.) The iMac, which has often been credited with saving Apple in 1998, incorporated some CHRP hardware ideas but did not stick rigorously to the CHRP standard.

By 2005, even the PowerPC chip was losing ground. Apple was becoming increasingly disappointed with Motorola’s inability to produce a PowerPC G5 chip that would reliably run at 3 gigahertz. Also, Motorola’s plans for future chip development did not match Apple’s plans for computer development. In January, 2006, Jobs made a shocking announcement: Henceforth, Apple would be using Intel’s Core and Core Duo chips as the brains of their computers. Many die-hard Apple loyalists decried the decision as selling out to the “Wintel” world, but as it became clear that the new Macintosh Pro line ran OS X just as well as the old PowerMacs, resistance subsided. Computers;compatibility Personal computers;compatibility IBM Apple Computer AIM alliance

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Carlton, Jim. Apple: The Inside Story of Intrigue, Egomania, and Business Blunders. New York: Random House, 1997. Corporate history of Apple, with some material on the AIM initiative.
  • citation-type="booksimple"

    xlink:type="simple">Duntemann, Jeff, and Ron Pronk. Inside the PowerPC Revolution: The Inside Story Behind the Chips, Software, and Machines That Are Changing the Computer Industry. Scottsdale, Ariz.: Coriolis Group Books, 1994. Specifically examines the history of the PowerPC chip.
  • citation-type="booksimple"

    xlink:type="simple">Levy, Steven. Insanely Great: The Life and Times of Macintosh, the Computer That Changed Everything. New York: Viking Penguin, 1994. Published on the tenth anniversary of the Macintosh, the book came out just as the AIM alliance was bearing fruit, and thus shows the enthusiasm of those heady days.
  • citation-type="booksimple"

    xlink:type="simple">Malone, Michael S. Infinite Loop: How Apple, the World’s Most Insanely Great Computer Company, Went Insane. New York: Doubleday, 1999. Examines some of Apple’s corporate politics related to the development and implementation of the PowerPC chip.
  • citation-type="booksimple"

    xlink:type="simple">Riordan, Michael, and Lillian Hoddeson. Crystal Fire: The Birth of the Information Age. New York: W. W. Norton, 1997. Helps place the microchip in the larger context of the convergence of information technology.

Intel Introduces the First “Computer on a Chip”

IBM Introduces Its Personal Computer

Introduction of the Apple Macintosh

Microsoft Releases the Windows Operating System

Categories: History