I am not an expert on power supply design at all, but to my untrained eye, http://oldcomputers.net/pet2001.html shows a more traditional power supply for the contemporary PET (the blue round thing looks like a huge capacitor; behind it, I think I see a traditional transformer) I googled for TRS-80 internals, too, but could not find them.
So, it _could_ be that having a switching power supply in a personal computer was innovate at the time.
Even magnified it's hard to tell from that photo, but I agree that honking big blue electrolytic capacitor indicates filtering of traditional low frequencies rather than the smaller caps you'd expect for a switcher.
Still, if you're shipping PET computers with a heavy glass CRT display on top, you're presumably not as concerned with weight as you would be with smaller form factors. So this evidence doesn't bear on the article's thesis. Given that the IC controllers introduced the year before the Apple II, the chip vendors would likely have already been sending out sample chips and application notes for some time, although their target engineering applications would be for products where cutting weight was a bigger concern than cost. (Hence Boschert's company having 650 employees in 1977 and having developed products for "satellites and the F-14 fighter aircraft".
I agree that the difference may be due to that CRT.
However, there are lots of other options:
- Steve was intentionelly lying.
- Steve was misinformed.
- Steve was misunderstood.
- the innovate part was getting out better quality DC than other solutions that did not use such an IC, and not using the IC was a serious advantage, cost wise.
- the innovative part was getting good enough power out at an insanely low price.
I guess we will never know. Archaeology is hard, even when talking about 35 years ago.
So, it _could_ be that having a switching power supply in a personal computer was innovate at the time.