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It's a cliche that PCB and microprocessors look like aerial
views of cities, so this has that issue, but I hope I've done
something new with it.
Design a city with enormously wide power cables clearly
visible from the air along with junctions to those power
cables which work as relays or storage
former wired together in such a way as to implement logic
gates. The top surface of everything in the city is painted
with contrasting paint and a literal outline of a component
which if realised in conductor plus insulator form would
work as the component it actually contains.
The components are buildings with continuous stripes of
contrasting colour down their walls which glow in the dark
or not according to whether they are insulators or
conductors. These join directly into an underslung
monorail transit system which is similarly painted on top
The entire city works as a CPU which happens to
implement a program which controls various aspects of the
city such as transport, utilities, stock control and logistics.
At night, the city lights up in strips rather than the usual
street lighting. This enables it to be photographed aerially
using old-fashioned silver compound emulsion type
techniques. If the photograph is then processed in the
right way, it will become a functional network of silver
wires on a plate which will itself function as an identical
CPU to the city itself.
There are a number of problems with this:
* I've been vague about the nature of the contrasting
colours. I've mentioned glowing, street lighting and so
forth, and I don't like that I've done that because it's made
it too vague.
* I'm not sure whether a method really exists whereby a
photographic emulsion can be completely converted to
metal plus insulating gaps. I do, however, think the
surface of the emulsion should be glassy rather than
* Only one layer of circuitry is possible, unlike a
* I'm not at all sure if silver in particular or any single layer
of metal can be used to realise electronic components. I'm
more or less confident it can be used to make capacitors
but the rest seems a bit implausible. In particular relays,
valves and transistors are all ruled out because there are
no moving parts, no evacuation, no ferromagnetism and no
semiconductors. Having said that, I wonder if a
photography technique could be developed that deposits
semiconductors, or whether that actually exists in the form
of however they make chips.
Home, sweet home ...
Baked and WKTE ... [8th of 7, Jan 26 2017]
A good article, includes the bit about how AMD made the 9080
search for the first occurrence of 'xerox' and read onward a few paragraphs. [Ian Tindale, Jan 26 2017]
Electron flow in transistors
Go to the third diagram, see how the electron flow is for NPN and PNP transistors. [Ian Tindale, Jan 26 2017]
||But we all know that the Borg cube is only a gigantic Rubik's Cube, accidentally manufactured with 1km sides due to a decimal point error when placing the online order through Shapeways. Just because you've peeled the stickers off doesn't make it clever, though it is big.
||Not to counteract anything you've said, but I'd add a few
||Start with something that isn't a microprocessor.
Microprocessors are wonderfully functional things, all in
one slab, but there's examples of other equally wonderful
integrations that aren't so big and yet are just as much fun.
I'd suggest something like the 555. In fact, not something
like it, I'd suggest it. It's smaller, easier to understand, and
yet contains a packet of tools that enable some fairly
definite functions and behaviours to happen. The 555 is
also very well understood and a fundamental block that is
used in teaching and actual industry even to this day
(although in actual use, the 7555 cmos version is
preferable, as it doesn't slam the power lines so brutally
upon output excursions).
||There is a method of converting photographic emulsion to
conductor and insulator patterns, because indeed all actual
chips and even microprocessors start their life as a
photographic film image. Indeed, AMD when they were
beginning out had to hand retouch the negatives of the cpu
they were working on, which contained errors in the repro
process. I'll post some links on the early days of AMD and
their 9080 copy of the Intel 8080 made from piecing
together photographs of the silicon die and redrawing it
back to the circuit. But yes, the die starts off as a negative
film (line film), and in those days, full of pinholes.
||Semiconductors should be able to be created simply by
making an 'in between' between a conductor and insulator.
To a certain extent, a resistor is that, but what we
generally mean by a semiconductor also incorporates
directionality, hence a diode allows greater electron flow in
one direction than another (and a transistor (which can be
thought of as two back to back diodes, because it is a three
layer sandwich of the two doping polarities) acts as a kind
of lever whereby the flow through two ends is contingent
on the level of energy on the middle connection). So, you'd
need not necessarily a semiconductor (which is just the
way we do it now, valves were not semiconductors) but
rather, you'd need the functional urban equivalent of a
||The other advantage of a 555 rather than a full cpu is that
you could do it on the scale of a village, or a town, rather
than a whole city.
||// you'd need the functional urban equivalent of a diode //
||It's called the Chiswick Flyover on the North Circular, and unfortunately it's Baked and WKTE.
||The Hogarth Roundabout flyover on the A4 is more
closely equivalent to a diode, surely?
||Well, are there any traffic systems that exhibit a behaviour
of a maximum flow from one end to the other, but
regulated by a flow into a middle? (Or out of, in the case of
NPN) (see page I've linked to here, no, not here, up there
||Actually, I just thought - a severe road traffic accident in
the opposite lane of a motorway has the effect of retarding
flow in the unaccidented lane as people slow down and
think about things for a while. This is essentially a field
effect, the accident is the gate exhibiting a field effect on
the flow between source and drain of a single doped layer,
as a normal FET is.
||And also, hippo, bicycles.
||Processor speed tends to go down as size increases, due to
the time it takes signals to travel from one part of the CPU
to other parts. A CPU as large as a city might be too slow to
handle the real-time city-data processing that was
in this Idea
||//Only one layer of circuitry is possible//
||Also <placeholder for bus-related pun>
||It would be problematic to take a photo of a subway from the air.
||I thought about clock speed and decided it should be asynchronous,
but yes, it might be slow.
||Synchronicity is overrated. Once we develop proper computers it will be seen as a very strange idea.