Quite interesting: https://www.youtube.com/watch?v=BcJ6UdDx1vg

I didn't quite understand all of it, but the gist seems that at certain frequencies a capacitor of a given value might have it's bypass ability nullified (for those frequencies). By putting multiple close values you reduce this effect (someone please correct me if I've read this wrong).

Perhaps this is something that we need to keep in mind for future 6502/65816 designs?

High-speed-digital design industry guru Dr. Howard Johnson has several short, good write-ups on the subject, indexed at https://web.archive.org/web/20120302190 ... capacitors . I remember him saying that for the capacitor closest to the IC pin, for a given package size and voltage (for example 0402, 16V), you might as well go for the greatest capacitance available, because its equivalent series inductance won't be any higher than that of a capacitor with less capacitance. One of the articles shows how to do the layout to get the least total inductance from the Vcc pin to ground. (Put the via to ground beside the capacitor, not out at the end, and of course keep traces so short they're almost non-existent.)

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

This is a technique that has been known since the days of vacuum tubes. Electrolytics, in particular, often have significant series inductance, and thus do a poor job of bypassing high frequencies. It's not uncommon to see a ceramic or mica capacitor in parallel with an electrolytic so as to compensate for this characteristic.

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

In my "overclocking to the extreme" experimentation on AVR and PIC, I often put my scope on the power rail and then drop in different capacitor values to observe the resulting noise.
It's amazing how placement can effect the results. Many times, it's not at all what one would expect, or what the experts would claim.
I have seen the multiple bypass cap effect work as well, especially on the large pin DIP AVRs.
Have even observed changes in the VCC noise by using a variable to "tweak" the best value.
You can never beat real world testing with any amount of theory!

Brad

Someone on the 6502 programming facebook group has on his timeline: "Theory is when you know everything but nothing works. Practice is when everything works but no one knows why. In our lab, theory and practice are combined: nothing works, and no one knows why."

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

... perfect!

Brad

I've always used 100nF bypass caps - one per IC. Perhaps I should have a look at 10nF and 1uF as in conjunction for high noise ICs such as the CPU.

Many of his videos are NSFW. Can anyone comment on this one?

Dave Jones' EEVblog is not safe for work? I'm surprised - that could only be robust language presumably? I don't hear any swearing so far, and unless he dropped an enormous 1970's disk drive on his foot I wouldn't especially expect any.

I don't remember him swearing or anything, but if in doubt use a set of headphones if your work place permits.

He uses coarse language at times (you can sometimes tell when it's going to happen, because the pitch of his voice goes from high to higher). But his language is quite tame compared to my every-day expletive-laden tirades, so his videos would definitely be safe at my work. Except, the boss took away our speakers, so ...

Mike B.

Smart boss.

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

It's mostly the unfortunate phrases he uses... "one hung low" and "in like Flynn" being the two most common. I don't think I'd get in trouble or anything, I just don't want to recommend that sort of thing to people in a professional environment without a NSFW warning first.

I can't quite imagine using out-loud audio at work - either headphones or a private office with a closed door would be a must, for me. (A very rare thing, the private office.) But then I've heard it said by sales types that our offices are like libraries. I'm sure sales people like lots of hubbub, but quiet concentration seems best for engineers.

Yeah, I have worked exclusively in adult-male-only blue-collar environments for over 30 years, so some crude habits have developed which I will need to diligently "unlearn" if I ever get off my @$$ and make the move to white-collar.

Mike B.