I came across this article.

http://www.righto.com/2012/02/apple-did ... power.html

It's a little old, but was a very interesting read. I have to admit that I was like so many other people in believing that the switching power supply "invented" by Rod Holt for the Apple II was revolutionary. Heck, he got two patents from it and Apple/Jobs made him somewhat famous for it.

I even remember the scene from Pirates of Silicon Valley when he was tasked at designing a PSU that was revolutionary.

Now, don't get me wrong, I have no ill-will towards Holt but that article sums up a lot of misinformation in computer history. I don't think anyone on this forum is more of an Apple II fanboy than me but I still get frustrated when I read the inaccuracies in what Apple claimed to do for computers.

Anyway...I thought it was a very interesting article that I wanted to share.

_________________
Cat; the other white meat.

Lots of great analysis on that site!

Steve Jobs missed his calling. He should have been a politician, given all the nonsense he spouted. For example, he famously opined in an interview with Playboy magazine in 1983 or 1984 (don't recall which) that most people were washed up after the age of 30, because once that age was passed one's creative abilities deteriorated.

From the article:


There's nothing obsolete about ferroresonant transformers. In fact, the UPS that supports our office servers and network gear is a 1.4 KVA ferroresonant unit that we acquired new in 2008. The manufacturer continues to produce these units in ratings up to 30 KVA.

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

Ahh, one of my pet hates - conventional power supplies are NOT linear in any form or manner. For a start, there are many, many variations. In an unregulated PSU made up of a transformer, bridge rectifier and smoothing capacitor(s), there aren’t even any transistors. And even when there are, a series pass transistor design, or a shunt regulator design uses the transistor in a mode that can be highly non-linear!

Also “linear power supplies are almost trivial to design and build“ was not true if we are talking about a design that had good regulation characteristics with reasonable current output, prior to the introduction of “modern” integrated circuits (that now make it easy). You try to design one using transistors, diodes, resistors and capacitors only. It’s hard to get a design that offers good performance and stays stable, as the pass transistor characteristics change as it heats up.

Oh, and all transistor based CRT type TVs and monitors have at least one switching power supply system in them - the line (horizontal) drive for the scan coils and EHT system... rather more common than any Apple 8 bit computers at the time.

[/rant ends]

Mark

PS makes you wonder if Apple / Steve Jobs were actually first with anything?

I'm sure Ken would appreciate a correction as a comment on his blog.

You'll also find him popping up as 'kens' on Hacker News, most recently in a discussion about core memory. He's done a number of investigations into the internals of the 6502 on his blog, as well as investigations into other micros and other now-vintage computers.

The term 'linear' as applied to power supplies or integrated circuits does not relate to the operational response of the device, but rather the physics of the device. In other words, the mathematical models describing two 'linear' systems can be combined in a mathematically linear fashion to form a third viable model.

So, if you have two systems described by the functions F and G and you feed the output of F into G to form a new combined system, then find the function H=G(F) accurately describes the new system, then F, G and H are linear systems. Note: Neither F or G needs to be linear in response.

A better term for things like linear integrated circuits or power supplies, etc... might be analog, as it makes more intuitive sense and does no call on theoretical rhetoric.

_________________
Bill

I didn't see an "post your comment" area on that page.

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

Jobs was a flim-flam man who flogged computers. I watched an interview with someone at Apple who said he was not technical but had a knack for knowing what piece of tech would sell. It irks me every time I see him given credit for a piece of technology he had no part in engineering. Woz was the brains in the early days, Jobs was a used car salesman.

Bill, the trouble with using linear in the way you described, is that it can also be used to describe DC/DC converters... As most SMPSUs are actually DC/DC converters with a conventional power supply input stage (yes, I know that larger SMPSUs now have the complexity of power factor correction)...

If the PSU is not operating beyond it’s full load, the output voltage should be a nice stable voltage (flat and smooth with no significant ripple). The DC input voltage to the switching stage may have some level of ripple, but if this is averaged out, it can be treated as a simple voltage. The input current can also be averaged out. The power output will then be proportional (in DC terms) to the input minus any losses. Does that now make the relationship linear? [yes, I know there are lots of if’s and buts and averaging].

I mainly don’t like the use of the word linear, as some people use the term to describe any power supply system that is not a switch mode type. As I said earlier, there are many different types of conventional power supply systems, some of which use SCRs (thyristors) in their operation (but are not called switch mode because they operate at mains frequency). It is in my humble opinion a very loose and misleading way to describe something. Just as it annoys me that 8 bit microprocessors (like the 65C02 and the Z80) are now often in the section of electronic suppliers labelled as microcontrollers

I have no objection to the use of the term analogue for conventional power supplies, as it is more appropriate

Mark

PS sorry if I have dragged this off topic

Hmm, I see a link right at the bottom of the page...

I scrolled to the end and at first didn't see anything. It then dawned on me the link might be a funky color. So I told the browser to display with no style and there it was.

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

I think he was more than that. He (usually) knew what tech would sell but also WHY it would sell. I agree that statements that say he invented the Mac or the personal computer or the portable music play are annoying and false. I'm not a Steve Jobs fanboy, but I do agree that computers were ugly before he came along. Now, I actually LOVE the "ugly" look of them but that's another topic.

Also, as much as I respect Woz, he's not much better. He's made some pretty hefty claims himself. He even wrote a book on how he invented the personal computer. Which is certainly up for debate. Your definition of "personal" may be different than mine. Not to mention you rarely hear about companies like Sphere that also had a "personal computer" back in the day.

You also rarely hear about Allen Baum or some of the other guys (other than Rod Holt) that had a significant influence on the Apple II. Or brilliant engineers like Burrell Smith for the Mac.

My theory is that it's a lot like the moon landing. If you didn't read your history books, you might assume that Buzz Aldrin was the first man on the moon because of the countless interviews he's done. I don't think I've ever seen a solid interview with Neil Armstrong.

_________________
Cat; the other white meat.

The 2 legit things that I will credit Jobs-led Apple with:

1) Creating a tablet form factor that isn't just a 2-inch thick laptop without a keyboard, as many were making at the time. To my understanding, Apple scored contracts with parts suppliers right before prices of applicable components went up, and thus was the only one making such things for a while. Certainly Jobs' demands on the device's size, shape, and weight were instrumental there.

2) Popularizing high-resolution LCDs. 200-300 dpi displays had existed for a while, in the IBM T221 and various small handheld devices, but nobody was really bringing them to the consumer market for desktop & laptop displays, which really annoyed me as I loves me them pixels. Again, this was likely a specifically Jobs thing to push those into the market.

Most everything else is just the Steve Jobs Reality Distortion Field, but I will applaud him for those 2 specific things.

_________________
WFDis Interactive 6502 Disassembler
AcheronVM: A Reconfigurable 16-bit Virtual CPU for the 6502 Microprocessor

I would add some more to that list (which I also agree with):

3) Designing a computer (or at least overseeing a design) that made the computer a centerpiece instead of an ugly box or plastic wedge that no one thought about. The Apple II (IMHO) was the first "beautiful" computer. And yes...beautiful is opinion and not fact. When I look through stories and posts from back then, even the haters usually admitted the thing looked good.

4) Putting "mostly" affordable desktop publishing into the hands of amateurs like my high school English teacher. Jobs even rejected color on the Mac for the longest time because GOOD color printers were out of reach for most people. When the first laser printers started becoming affordable, and the B/W Mac with its (for the time) sharp display, desktop publishing was really starting to reflect the WYSIWYG. Atari and Amiga had superior computers in almost every way. Except sales and software! That was because of Jobs.

_________________
Cat; the other white meat.

I'll add my two cents worth, rightly or wrongly:

(1) Building the ability to deal with consumer product demands by building the iPod.
(2) Essentially betting the company that it could build an iPhone like it did the iPod.

I don't know whether Apple would have become the valuable company that it is today unless it developed these two products, which were clearly driven by Jobs in one way or another. Good computers the Apple way are still not enough to entice me to pay their asking price.

_________________
Michael A.