It’s easy to forget, in the wake of Tuesday’s Apple-IBM announcement, that IBM played the heavy for most of Apple’s early years, from Steve Jobs’ cheeky 1981 Wall Street Journal ad (“Welcome, IBM. Seriously.”) to the 1984 Superbowl spot that cast Big Blue as Orwell’s Big Brother.

But as Asymco‘s Horace Dediu points out, IBM IBM was always a reluctant PC maker. It never controlled the PC platform the way it did its mainframe business, and after the 1990 falling out with Microsoft MSFT , the company found in Apple if not a kindred spirit, at least a partner that feared the power of the Windows-Intel (WinTel) axis as much as it did.

IBM and Apple formed three alliances in the early 1990s: PowerPC, Taligent and OpenDoc. None turned out well.

  • PowerPC was a joint venture of Apple, IBM and Motorola — the so-called AIM alliance. Based on reduced instruction set chip (RISC) technology IBM had developed, the PowerPC was designed to compete with Intel for the PC business. But except for the Macintosh, which it powered from 1994 to 2006, it mostly found a home in video games and other embedded systems. In 2006, Steve Jobs famously abandoned PowerPC and switched to Intel’s INTC chips.
  • Taligent was a early object oriented programming language begun at Apple and later spun off to IBM. “In 1992,” wrote Macworld two years later, “the earth shook: IBM and Apple clasped hands and pronounced themselves allies. From this union sprang Taligent.” By 1995, Apple had lost interest in the project. IBM pulled the plug a few years later.
  • OpenDoc was a software standard developed by Apple as an answer to Microsoft’s Object Linking and Embedding (OLE) framework. In 1992 it brought into the OpenDoc fold WordPerfect and IBM — both bitter enemies of Microsoft. When Steve Jobs returned to Apple in 1997, one of the first things he did was “put a bullet through [OpenDoc’s] head” (his words).

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The partnership that IBM and Apple announced on Tuesday looks to be very different kind of deal — not a defensive technology or product play, but a strategic marriage of equals with complementary strengths. According to Apple’s press release the two companies are working together to deliver “the essential elements of enterprise mobile solutions.”

Specifically: (I quote)

  • Mobile solutions that transform business: The companies will collaborate to build IBM MobileFirst for iOS Solutions—a new class of “made-for-business apps” targeting specific industry issues or opportunities in retail, healthcare, banking, travel and transportation, telecommunications and insurance, among others, that will become available starting this fall and into 2015.
  • Mobile platform: The IBM MobileFirst Platform for iOS will deliver the services required for an end-to-end enterprise capability, from analytics, workflow and cloud storage, to fleet-scale device management, security and integration. Enhanced mobile management includes a private app catalog, data and transaction security services, and productivity suite for all IBM MobileFirst for iOS solutions. In addition to on-premise software solutions, all these services will be available on Bluemix—IBM’s development platform on the IBM Cloud Marketplace.
  • Mobile service and support: AppleCare for Enterprise will provide IT departments and end users with 24/7 assistance from Apple’s award-winning customer support group, with on-site service delivered by IBM.
  • Packaged service offerings: IBM is introducing IBM MobileFirst Supply and Management for device supply, activation and management services for iPhone and iPad, with leasing options.

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Sounds like a plan.

See also: Apple and IBM partner to launch ‘made-for-business’ apps

Video update: Apple’s Tim Cook and IBM’s Ginni Rometty made a joint appearance on CNBC.

Follow Philip Elmer-DeWitt on Twitter at @philiped. Read his Apple AAPL coverage at fortune.com/ped or subscribe (free!) via his RSS feed.