Steves Jobs would've had you believe that the computer industry ripped off Apple's idea to use a switcher as their power supply in the Apple II. Reality is, of course, rather different -- this is an interesting article that provides a well-researched history of what really happened:
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Not that Jobs and Apple didn't create many innovations, of course.
Switching power supplies were used in computers when Steve Jobs was likely still in diapers. I worked on a switching supply out of an SDS computer that was probably built before 1965. IBM 360's had an innovative sort of a switching supply. They had a huge box in the back of the 360/50 and 65 called the converter/inverter. It took 208 3-phase power, converted to DC and then ran an SCR inverter at 5 KHz. Then, 5 KHz pseudo sine-wave power was run to all the local power supplies, like
5 V 100 A, which had minimal regulation due to regulated input. I'm sure there were other systems that also used switching regulators quite early. The PDP-11/45 had a bunch or switching regulator modules to produce 5 V and memory/aux voltages, not sure exactly when that model came out, but also pre-Apple, i suspect.
TDK credits NASA with developing SMPS designs for spacecraft in the early 1960s.. and they say they and the predecessor to Lambda started manufacturing them "about 1970". Of course, the original 1976 Apple I had a linear supply (60Hz transformer not supplied).
Any idea what current PC power supplies' switching frequency is? I've read that the good quality (power efficient) ones these days have moved to resonant architectures, which I remember for years being told was one of those technologies that was too complex or fiddly to ever take beyond the lab and into full production -- particularly for consumer electronics!
I mean, I'm still astonished when I see a regular PC-sized power supply and the specs on the thing are that it can put out a kilowatt at a guaranteed minimum efficiency of 80% and peak efficiency of 95% or so.
SDS had the same thing. The PT-15 (I think, I'd have to pull out the manual) took the AC and converted to a DC square wave that was fed to the local supplies in the door frames.
Mechanically chopped DC fed to a step-up transformer was common to both automotive tube radios and to the earliest car ignitions. The tube sets did use a rectifier, though.
I worked at SDS, mainly on Sigms 6/7/9. Switching power supplies all over the place.
I also worked at some S-100 companies (8080/Z80 based systems) before joining Apple in 1980.
The competing S-100 systems had linear supplies -- huge, heavy transformers.
One of the places Apple innovated was having an inexpensive, consumer-grade switching supply (thanks to Rod Holt, among others).
I remember being at some of those early West Coast Computer Faires and looking at the Apple ][ in comparison to my company's S-100 system -- the Apple ][ was so light. I remember thinking if they'd had an upper/lower case keyboard and an 80 character display on the early Apple ][ computers (both features came later), we'd be so screwed...
SO yes, the use of a switching supply in a multi-slot was a big distinguishing factor in that early micro market, one which spoke to a fundamental difference between Apple and companies like North Star, SOL, Poly, IMSAI, SWTPC, and the others -- Apple was backed by a LOT of money, enough money that they could afford that molded case (and the tooling to produce it), those switching supplies, and more.
Where'd their money come from? I was under the impression that they were still operating a shoe-string budget for the Apple II, just having made enough on the Apple I kits that they could manage to pull off its successor there.
Last year I read the book, "Founders at Work: Stories of Startups' Early Days." There's a pretty clear pattern in it that beginning in about the '90s, most (but not all) companies that ended up being successful were financed via large chunks of venture capital -- even when they were software companies, so it wasn't like they typical needed large capital equipment purchases (...although buying 100 servers at a shot isn't cheap, I suppose). Prior it seems like far more companies were self- or privately-financed...
Mark Zuckerburg and Facebook would be once exception to the pattern above, I suppose. I'm still amazed at just how popular Facebook is...
The two Steves put together a marketing pitch for their company. In looking around for someone to help tune up that pitch, someone pointed them to Mike Markkula, who had semi-retired at age 32 after raking in bushels of money from Fairchild Semiconductor, and another Silicon Valley startup, Intel.
Mike liked the idea so much that he became Apple employee #3, with the two Steves being #1 and #2.
Markkula brought in more than bushels of money. He instigated bringing in a lot of he early engineering talent, including Rod Holt (power supplies and analog design) Wendell Sander (making dram work reliably), Mike Scott (Scotty) who had been director of manufacturing at National Semiconductor and so many more, with expertise in engineering and manufacturing.
The talent and money that Markkula brought in made it possible to take the Apple ][ into volume manufacturing, something none of the S-100 companies were able to do.
Not sure those were really switchers. How else to get the relatively high voltage B+ from a low voltage battery? Did they even regulate them? Probably an LC filter on the rectified output was considered regulation back then.
Apple (or Steve if you insist) pushed a lot of good ideas that existed but were underutilized, over the high cost-low market penetration hump into mass production. Here's a partial list:
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