I had hands on experience of multilayered PCBs back in 1987 working as
an engineer in the video games repair industry.
Good for you, now would you feel it's reasonable for anyone
else to insist that they "know" for certain how one of those
1987 PCBs was designed based on their observation of a
modern PC motherboard, when every single board you've ever
seen from '87 was NOT like that "anyone" insists they are?
Generaly theory that multiple layers can allow a trace not
seen, is not evidence that this IS how and why LM&C observed
what he did.
I have. More than you it would seem.
Again you fail to grasp the obvious... that you would have
to actually examine modern motherboards to have any
applicable evidence. A theory about what "could" be, is not
the same thing as evidence of it actually being true.
I know exactly what is normally seen. I also know that some functions
have ended up being integrated into ICs themselves. As well as that, my
background comes from an industry which routinely scrubbed numbers off
chips and also misnumbered them to prevent piracy.
No, you clearly have no clue about what is normally seen.
Look on the motherboard in the system you're using RIGHT
NOW. Dig a few dozen out of a closet and look at them.
Look online at good pictures. Your "opinion" is worth
little if it is not consistent with actual boards.
Would you agree than when the surface-layer's pads ARE
populated with a fuse (or a jumper, inductor, 0-Ohm
resistor, or trace closing the two fuse pads) that it would
be pointless when there is also a parallel power trace in an
underlying layer? Certainly anyone with as much circuit
board experience as you claim would at least recongnize this
basic electrical fact, that one cannot fuse one of two
parallel supply lines and have the fuse be useful.
Therefore there is no point to having surface-mount pads
unless the inner layer is reworked.
Is this what you claim, that they redesign and remanufacture
boards with a different inner layer every time? That would
be quite the opposite of this "universal" board concept you
claimed where they can use one board with ommision of some
surface-mount components based on need.
For one, because they have them on the top layer. I've
already mentioned the issues surrounding parallel lines and
inner layer rework for supposed universal boards.
So they're there. SO FUCKING WHAT?
So you're not using evidence or any thorough evaluation of
whether your idea is reasonable, merely making a passing
comment about internal layers is just an educated guess...
but not all that educated because you are not using ANY
modern motherboards as examples, while there are absolutely
zero reports of any boards (thus far) that actually employ
what you're guessing they do.
I can show you 20 CB radios from one
manufacturers, all based on the same board layout. On each model, the
PCB is the same but the components differ with blanks being left for
unused sections.
You have fallen victim to a common human delusion, that if
someone has a lot of experience in something loosely
related, they suddenly become an expert on that other topic
too.
Yes, the PCB can have unused pads filled as needed. The
WHOLE point of doing this is to avoid having to rework the
circuit traces every time. If there are inner layers which
short parallel paths to those available on the top layer,
there is no point to having the top layer traces in ANY
implementation of features (or lack thereof).