What did the PC future look like back in 1989? Take a trip in the Wayback Machine in this speech from Bill Gates. Gates and his execs should listen to it as well, because there’s an unintended warning in it for the future of MIcrosoft.

Remember the 640K memory barrier? EGA graphics? How about WYSIWIG editors? You’ll hear about all that, and about the early days of DOS as well. You’ll hear about an Apple/Microsoft lawsuit, and the now-defunct OS/2.

You’ll also hear about the first consumer-level, mass-audience computer, the Altair 880, and how Gates and Paul Allen wrote a version of BASIC for it. He also provides a fascinating look into the very earliest days of programming for microcomputers.

It’s a fascinating speech, as Gates traces the history of the PC development, from its very earliest days, and outlines his role in it.

But there’s one unintended piece of irony in it. He talks about when IBM came to Microsoft, and asked that the company build an operating system for its new, top-secret microcomputer, which would become the PC. Gates says that part of the reason for the IBM project wasn’t just to launch a new computer — it was to prove that notoriously slow-moving IBM was capable of completing a project in a mere two years.

He got a great deal of laughter from that line.

I don’t think he’s laughing now, though. Two years? Microsoft should be so lucky as to complete a big project in two years. Vista, after all, took five. And although the next version of Windows most likely won’t take five years, it will certainly take more than two.

So perhaps this speech should be a must-listen for the current generation of Microsoft execs, as a reminder that it’s time to build a leaner, faster-moving company.