Steve Jobs had essentially retired from Apple Inc.’s day to day management back in January. On Wednesday he simply made this move official.

Thus ends the second (third, if you count the NExT/early Pixar years) era of Jobs’s involvement in, and leadership of, the digital gizmo industry.

I will leave it to others more laser-focused on that industry to give the big picture of Jobs’s work and legacy. But here are a few notes on it.

Jobs and Steve Wozniac did not, by themselves, “invent the personal computer.” Many individuals and companies had seen what the early mainframes could potentially do in the hands of smaller-than-corporate users. The early “hacker culture” was a tribe of programmers who worked in corporate, institutional, and particularly collegiate computing centers, who snuck in personal projects whenever and wherever they could get processor time.

As the first microprocessor chips came on the market, several outfits came up with primitive programmable computer-like devices built around them, initially offering them in kit form. One of those kit computers was Jobs and Wozniak’s Apple (posthumously renamed the Apple I).

That begat the pre-assembled (but still user-expandable) Apple II. It came out around the same time as Commodore and Radio Shack’s similar offerings. But unlike those two companies, the two Steves had nerd street cred. This carefully crafted brand image, that Apple was the microcomputer made by and for “real” computer enthusiasts, helped the company outlast the Eagles, Osbornes, Kaypros, Colecos, and Tandons.

Then the IBM PC came along—and with it MS-DOS, and the PC clones, and eventually Windows.

In response, Jobs and co. made the Apple III (a failure).

Then the Lisa (a failure, but with that vital Xerox-borrowed graphic interface).

Then came the original Macintosh.

A heavily stripped-down scion of the Lisa, it was originally capable of not much besides enthralling and inspiring tens of thousands into seeing “computers” for potential beyond the mere manipulation of text and data.

The Mac slowly began to fulfill this potential as it gained more memory, more software, and more peripherals, particularly the Apple laser printer that made “desktop publishing” a thing.

But Jobs would be gone by then. Driven out by his own associates, he left behind a company neither he nor anyone else could effectively run.

Jobs created the NExT computer (a failure, but the machine on which Tim Berners-Lee created the World Wide Web), and bought Pixar (where my ol’ high school pal Brad Bird would direct The Incredibles and Ratatouille).

The Mac lived, but didn’t thrive, in the niche markets of schools and graphic design. But even there, the Windows platform, with its multiple hardware vendors under Microsoft’s OS control, threatened to finally smother its only remaining rival.

Back came Jobs, in a sequence of maneuvers even more complicated than those that had gotten him out of the company.

Out went the Newton, the Pippin, the rainbow logo hues. In came the candy colored iMac and OS X.

And in came a new business model, that of “digital media.”

There had been a number of computer audio and video formats; many of them Windows-only. For the Mac to survive, Apple had to have its own audio and video formats, and they had to become “industry standards” by being ported to Windows.

Thus, iTunes.

And, from there, the iTunes Store, the iPod, the iPhone, the iPad, and an Apple that was less a computer company and more a media-player-making and media-selling company. The world’s “biggest” company, by stock value, for a few moments last week.

Jobs turned a strategy to survive into a means to thrive.

Along the way he helped to “disrupt” (to use a favorite Wired magazine cliche) the music, video, TV,  cell-phone, casual gaming, book publishing, and other industries.

We have all been affected by Jobs, his products, and the design and business creations devised under his helm.

He’s backing away for health reasons. But we’ve all been the subjects of his own experiments, his treatments for “conditions” the world didn’t know it had.

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The post-Jobs Apple is led by operations chief Tim Cook, whom Gawker is already calling “the most powerful gay man in America.” That’s based on speculation and rumor. Cook hasn’t actually outed himself, keeping his private life private.