explain xkcd - User contributions [en]

2497: Logic Gates

2021-08-03T16:07:38Z

141.101.99.204: /* Explanation */ But only a glance!

{{comic
| number = 2497
| date = August 2, 2021
| title = Logic Gates
| image = logic_gates.png
| titletext = In C, the multiocular O represents the bitwise norxondor gorgonax.
}}

==Explanation==
{{incomplete|Created by a SILICON LOGIC GATE TO A DIFFERENT DIMENSION. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

The comic lists logic gates. The first six are real, but the last six are made up and get increasingly absurd. The names for these last six are made up of the same letters and syllables as the first six so as to appear at a glance to be consistent with their naming conventions.

An AND gate outputs true if and only if both inputs are true. (Inputs 1 '''and''' 2 must be true.) By convention it is a symbol with a flat input end leading to a semicircular output end.

An OR gate outputs true if one or the other or both of the inputs are true. (Input 1 '''or''' 2 may be true.) By convention it is a symbol with a concave input edge leading to an output end resembling a gothic pointed-arch, reorientated as required.

A NOT gate outputs true if and only if the input is false. (The sole input must '''not''' be true.) The convention for the isolated NOT gate is to be a triangle (reminiscent of a diode or op-amp comparitor), that conspiciously points in the direction of logical passage, tipped with the small circle that is considered a short-cut for ''not''ness in other relevent symbols. The XAND GORT gate could be considered a NOT gate with two wires shorted together connected to its input.

A NOR gate outputs true if and only if both inputs are false. (Neither 1 '''nor''' 2 must be true; alternately interpreted as it must '''n'''ot be true that either 1 '''or''' 2 are true.) The symbol is the OR shape with the NOT-circle at its tip.

A XOR (short for “eXclusive OR”) gate outputs true if one, or the other, but not both of the inputs are true. (Mutually e'''x'''cusively, either 1 '''or''' 2 must be true.) This symbol is the standard OR one but with a further concave line stood-off slightly from the usual one to connect to the input lines.

A NAND (short for “Not AND”) gate outputs true if one or the other or both of the inputs is false. (It must '''n'''ot be true that both 1 '''and''' 2 are true.) The symbol is the AND gate with the NOT-circle at its tip.

The only real-life logic gate that was omitted is the XNOR gate (short for “eXclusive Not OR”; it compares the inputs, and if and only if they are equal, it outputs true). Note that the "NORG XORT" gate would be logically equivalent to it if it were tipped to match its uniquely XOR-style tail, since it would then be an XNOR gate with NOT on both inputs, a modification that has no ultimate effect on the logic as it merely switches the case of which exclusivity it needs to be, and does not care which version of same-input it might be responding to.

A double-NOT on an input would produce the identical output again (...if the input is '''not not''' true). Two NOTs preapplied to a (N)AND or (N)OR would produce the same output as a (further-)NOTted version of the (N)OR or (N)AND, conversly (...if '''not'''-1 '''and''' '''not'''-2 then this also means that neither 1 '''nor''' 2). Normally this would would be shown, if necessary, as full NOT gates on the lead-in inputs but (see Transcript, below, and the NORG XORT description above) the shortcut element is occasionally used in further mix'n'match symbology (together with reinterpreting connectivity lines as partial shape-edges and vice-versa) in 'understandable' but definitely non-standard ways.

Along with the deliberate confusion of connector and shape-edge lines, directionality is also played with in several cases, with input 'ends' perhaps also at the (implied) output end and reversed sub-symbols implying a composite gate with substructural feedback or perhaps diode-rectification upon a bidirectional logic path.

Much like [[2360: Common Star Types]], as the list progresses, the names start to sound more like mythical creatures, closing with the "Norxondor gorgonax". As with the symbology, the names appear to be nonsensical recombinations of the standard ones (perhaps with off-subject inspirations, in some cases) but often do not match up with the symbolic (mis)use, such as an X in the name not implying/being implied by an XOR's unique drawn feature.

In the title text [[Randall]] claims that in the {{w|C (programming language)|programming language C}} the {{w|multiocular O}} (ꙮ) character is used to represent the bitwise version of the last operator Norxondor gorgonax (presumably ꙮꙮ represents the non-bitwise version), fitting as the multiocular O is used to refer to "many-eyed {{w|seraphim}}" (i.e. angels) in some religious literature. {{w|Gorgon}}s (beige or otherwise) have heads covered with snakes instead of hair, and so possess multiple eyes, the most famous was known as {{w|Medusa}} (which was [https://www.explainxkcd.com/wiki/images/e/e5/1608_1088x1074y_Medusa_and_floating_earth.png depicted] in [[1608: Hoverboard]]).

C is a low level programming language, and as such, it has many operations that correspond to logical (i. e. bitwise) operations. These contrast with operations that work in a non-bitwise way. For example, "&&" is the non-bitwise "AND" operator that takes the operands as a whole, while "&" is the bitwise "AND" that combines the respective bits of its two inputs independently before spitting out the new single composite value the output bits represent. In non-bitwise operations, 0 always represents "FALSE", while any non-zero value means "TRUE" for inputs, and 1 is used to represent TRUE for outputs. Thus, "14 && 3" gives the result 1: TRUE AND TRUE -> TRUE. In the bitwise operation, using the same values, the decimal value 14 has the binary value 1110 and the decimal value 3 has the binary value 0011, and for this example we get:

1110 = 14
& <u>0011</u> = 3
0010 = 2

==Transcript==
:[The comic shows a chart with twelve electronic logic gates arranged in three rows of four. Each gate is depicted as a schematic symbol, with a label underneath. Above them is a header:]
:Common logic gate symbols

:[Here below follows a description of the 12 gates in the three rows, with their label given beneath each description:]

:[A standard gate symbol used in real life. Two inputs on the left lead to the vertical left edge of a solid D-shaped symbol. From the right side of the D there is one output.]
:AND gate

:[A standard gate symbol used in real life. Two inputs on the left lead to a convex-crescent left edge of a crescent-shaped symbol. The right side of the crescent symbol's shape forms a point at its output. From the right side of the crescent there is one output.]
:OR gate

:[A standard gate symbol used in real life. One input leads to a triangular symbol pointing to the right. There is a small bubble symbol connected to the triangle on the output, which leads right.]
:NOT gate

:[A standard gate symbol used in real life. This is identical to the OR GATE, except the output has a bubble attached, like the NOT GATE's output.)
:NOR gate

:[A standard gate symbol used in real life. This is identical to the OR GATE, except the left-hand arc at the input has a double-stroked line.]
:XOR gate

:[A standard gate symbol used in real life. This is identical to the AND GATE, except the output has a bubble attached, like the NOT GATE's output.]
:NAND gate

:[An unusual symbol. This symbol has one input on the left leading to a convex-crescent left edge, like the OR GATE. The output side as a smooth crescent like the AND GATE but has two outputs.]
:NORX gate

:[An unusual symbol. This symbol has two inputs on the left leading to a vertical left edge input, like the AND GATE. The output side has a convex-crescent double-stroked output like the mirror image of the XOR GATE's input. There are two outputs.]
:GAND ate

:[An unusual symbol. This resembles the NOT GATE except there are two inputs instead of one leading into the left side.]
:XAND gort

:[An unusual symbol. This has a double-stroked convex-crescent input like the XOR GATE, but the two inputs have bubbles attached. The single output has a smooth crescent shape with a bubble, like a NAND GATE.]
:NORG xort

:[An unusual symbol. Two inputs lead to a convex-crescent edge, and the two lines of this symbol now enter a double-stroked convex-crescent input like the XOR GATE. The two lines of -this- symbol have bubbles placed half way across their horizontal length, and are presumably the outputs.]
:ANDORX gant

:[An unusual symbol. The symbol is identical to the NOR GATE, except the upper and lower horizontal parts of the symbols hull have a NOT GATE placed on them - one pointing to the left on the upper line, and to the right on the lower line. There is one output to the symbol, with a bubble attached.]
:NORXONDOR gorgonax

{{comic discussion}}

[[Category:Charts]]
[[Category:Programming]]

Talk:2492: Commonly Mispronounced Equations

2021-07-22T06:42:02Z

141.101.99.204:

I think the wave equation is wrong based on units, but it's been a while. The wave speed ought to be squared. Of course, ''c'' could be a squared speed, but it's usually not. [[Special:Contributions/172.70.34.164|172.70.34.164]] 01:22, 22 July 2021 (UTC)

:I agree, normally it's written as C squared... The equations in order are 1: Gravitational Attraction, 2: Einstein's Mass / Energy Conversion, 3: Pythagorean Theorem (triangle side relations), 4: Area of a Circle, 5: Entropy equation, 6: Ideal Gas Law, 7: Euler's Identity, 8: Newtons Second law, 9: Wave equation, 10: The derivative of a function f, and, 11: The Quadratic Equation... I don't understand the linguistic rules being applied to the names, but they seem to be visual as much as anything [[Special:Contributions/108.162.237.66|108.162.237.66]] 02:04, 22 July 2021 (UTC)
::You should turn that into a table in the explanation. We can have a column where we try to come up with the pronunciation rule. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 04:10, 22 July 2021 (UTC)

The equation for the thing I have as what it was made by is
L
=
i
ψ
¯
γ
μ
∂
μ
ψ
−
e
ψ
¯
γ
μ
(
A
μ
+
B
μ
)
ψ
−
m
ψ
¯
ψ
1
4
F
μ
ν
F
μ
ν
.
{\displaystyle {\mathcal {L}}=i{\bar {\psi }}\gamma ^{\mu }\partial _{\mu }\psi -e{\bar {\psi }}\gamma ^{\mu }(A_{\mu }+B_{\mu })\psi -m{\bar {\psi }}\psi -{\frac {1}{4}}F_{\mu \nu }F^{\mu \nu }.}

when copy-pasted from Wikipedia. {{w|Quantum electrodynamics#Equations_of_motion|here is the link:}} [https://en.m.wikipedia.org/wiki/Quantum_electrodynamics#Equations_of_motion These are both the links.]
For archival, this is the thing: LAGRONJ EYSIBARYMOODMOOSIOYLERSIBRYMOOAMOOBAMOOSIMASIBRSIQORTFAHMOOVYFAHMOOVY.
[[User:4D4850|4D4850]] ([[User talk:4D4850|talk]]) 02:22, 22 July 2021 (UTC)

My friends and I actually pretty often say "PəV-nert" for the ideal gas law. First syllable is kind of vowel-less, sort of a schwa if anything. But also stressed? Didn't know you could stress a schwa but, guess I did.
[[Special:Contributions/172.70.130.160|172.70.130.160]] 02:36, 22 July 2021 (UTC)

I think this is the XKCD that has made me laugh the most, out of all 2492.
:I'd say it might be the one that made me laugh the most, out of all {{LATESTCOMIC}}. I won't, because it didn't, but I could. --[[User:4D4850|4D4850]] ([[User talk:4D4850|talk]]) 03:23, 22 July 2021 (UTC)

I tried to transcribe these pronunciations into IPA, because reading them like this is kind of ambiguous. I probably got a bunch of stuff wrong though.
fəˈdʒæmɚ |
ˈɛmkɑˌtu |
ætˈbutkut |
ˈæpɚˌtu |
həˈsplɒgpi |
ˈpævnɚt |
ˈaɪpɪn |
ˈfimɑ |
dut kəˈduks |
ˈfækslɪmˌoʊ ˈfæksəˌfɒx |
zəˈbɔbə fækˈtoʊɑ |
ˌɛpsɪˈhutəˌmu ˈdupsɪˌkwɔrps

Why is it a soft G in the gravity equation? [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 04:10, 22 July 2021 (UTC)
:I believe it's a reference to the "gif" pronunciation debate. "Fuh-gam-er" is the obvious pronunciation, Randal is facetiously asserting "Fuh-jam-er" is correct.--[[Special:Contributions/108.162.250.130|108.162.250.130]] 05:00, 22 July 2021 (UTC)

The most similar time when equations are actually 'pronounced' a bit like this is the "soh cah toa" mnemonic for the trigonometric identities - should this be in the explanation? (the comic made at least me think that might be the original inspiration) [[Special:Contributions/141.101.99.204|141.101.99.204]] 06:42, 22 July 2021 (UTC)

730: Circuit Diagram

2021-02-26T23:31:01Z

141.101.99.204: /* Explanation */

{{comic
| number = 730
| date = April 21, 2010
| title = Circuit Diagram
| image = circuit_diagram.png
| titletext = I just caught myself idly trying to work out what that resistor mass would actually be, and realized I had self-nerd-sniped.
}}

==Explanation==
Another fine example of [[356|nerd sniping]], as mentioned in the title text.
There are pieces of circuit diagrams, road maps, chemical diagrams, and other things all mixed in.
Explanations for each below!

{|class="wikitable table-padding left-align"
!Image Fragment
!width="130px" | Image Location
!Description
|-
{{circuit-diagram-part|X=19|Y=25|W=106|H=37|image=circuit_diagram-019-025-106-037-scale.png|text=A map scale. Lists kilometers and miles as equivalent. And makes the diagram many miles wide.}}
{{circuit-diagram-part|X=15|Y=62|W=40|H=85|image=circuit_diagram-015-062-040-085-antenna.png|text=An antenna. Typical of radio receivers or transmitters. Or the Turtle in {{w|Logo (programming language)|LOGO programming language}}.}}
{{circuit-diagram-part|X=53|Y=60|W=41|H=87|image=circuit_diagram-053-060-041-087-inductor.png|text=A coil or {{w|inductor}}. Normal, but unlabeled.}}
{{circuit-diagram-part|X=107|Y=86|W=85|H=93|image=circuit_diagram-107-086-085-093-cloverleaf.png|text=A {{w|cloverleaf interchange}} or junction is a feature of road networks that does not belong in a circuit diagram. Of course, other types of {{w|p–n junction|junction}} are important in electronics.
A cloverleaf junction has previously been used in comic: [[253: Highway Engineer Pranks]].}}
{{circuit-diagram-part|X=184|Y=12|W=87|H=63|image=circuit_diagram-184-012-087-063-battery.png|text=A battery. The voltage of square root of two is strange, but getting about 1.41412... volts is not unheard of. This could also indicate an [[wikipedia:Root_mean_square|RMS]] voltage, although this is unlikely given that this is a DC power supply and not an AC generator. The marked polarity is also the reverse of what is implied by the symbol (where the larger terminal is positive). A possible reference to [[567: Urgent Mission]].}}
{{circuit-diagram-part|X=187|Y=110|W=94|H=71|image=circuit_diagram-187-110-094-071-resister.png|text=A 120 ohm {{w|resistor}} is normal enough. "Or to taste" is odd for a circuit diagram and more like instructions from a recipe, e.g., "1 tbsp tomato purée, or to taste".}}
{{circuit-diagram-part|X=283|Y=50|W=90|H=63|image=circuit_diagram-283-050-090-063-switch.png|text=A normal {{w|switch}}, with a notation to glue it open. Reminiscent of the [http://catb.org/esr/jargon/html/magic-story.html MAGIC/MORE MAGIC] switch.}}
{{circuit-diagram-part|X=337|Y=101|W=69|H=64|image=circuit_diagram-337-101-069-064-transisitor.png|text=A {{w|Bipolar_junction_transistor#PNP|bipolar PNP transistor}}, except that it has two emitters and no collector. It also resembles one of the schematic symbols for a {{w|DIAC}}, except the arrows are backwards.}}
{{circuit-diagram-part|X=52|Y=141|W=79|H=107|image=circuit_diagram-052-141-079-107-compass-points.png|text=Compass points. A map feature, not a circuit feature, but possibly useful given the circuit is many miles wide.}}
{{circuit-diagram-part|X=415|Y=18|W=63|H=58|image=circuit_diagram-415-018-063-058-resister.png|text=A normal resistor, labeled with color code. Brown-Blue-Orange would be 16000 ohms. {{w|Electronic color code|Resistor color codes}} are for reading the value on the physical device itself. They would not normally be shown on the circuit diagram, where it's much easier to just write the number, e.g. 16K.}}
{{circuit-diagram-part|X=517|Y=14|W=42|H=32|image=circuit_diagram-517-014-042-032-diode.png|text=A normal {{w|diode}}.}}
{{circuit-diagram-part|X=615|Y=55|W=73|H=74|image=circuit_diagram-615-055-073-074-666timer.png|text=A chip. The normal timer is a "{{w|555_timer_IC|555}}". "666" would be the number of the beast in [http://www.blueletterbible.org/Bible.cfm?b=Rev&c=13&v=18&t=KJV#18 Rev. 13:18]. The pin connected to "?" is the CTRL pin on a normal 555 timer, which would typically be connected to ground (via a decoupling capacitor) if used at all; the implication here seems to be that it would be connected directly to Hell itself.}}
{{circuit-diagram-part|X=632|Y=138|W=69|H=41|image=circuit_diagram-632-138-069-041-bat.png|text=A Batman logo.}}
{{circuit-diagram-part|X=650|Y=211|W=75|H=71|image=circuit_diagram-650-211-075-071-squirrel.png|text=A squirrel, or perhaps a wire bent into the shape of a squirrel. {{w|Electrical disruptions caused by squirrels|Squirrels are among the leading causes of disruptions to electrical grids,}} so having one as part of a circuit is inviting disaster. Squirrels also appear in past and future xkcd comics.}}
{{circuit-diagram-part|X=606|Y=165|W=54|H=53|image=circuit_diagram-606-165-054-053-inductor.png|text=A coil or inductor, or a spring symbol in Physics force diagrams, probably the latter as it is labeled with an 11-kilogram mass.}}
{{circuit-diagram-part|X=538|Y=209|W=99|H=59|image=circuit_diagram-538-209-099-059-generator.png|text=A 240-volt AC generator (or other power source).}}
{{circuit-diagram-part|X=483|Y=186|W=111|H=103|image=circuit_diagram-483-186-111-103-shorted-generator.png|text=A shorting wire around a generator. The label reads "Omit this if you're a '''wimp.'''" If this wire is included, it will quickly melt - or worse.}}
{{circuit-diagram-part|X=419|Y=78|W=57|H=75|image=circuit_diagram-419-078-057-075-scarab-beetles.png|text=A jar of {{w|Scarabaeidae|scarab beetles}}.}}
{{circuit-diagram-part|X=482|Y=47|W=28|H=44|image=circuit_diagram-482-047-028-044-variable-resister.png|text=A {{w|variable resistor}} with center tap. Normally, there would be an arrowhead on the center tap.}}
{{circuit-diagram-part|X=507|Y=53|W=22|H=27|image=circuit_diagram-507-053-022-027-capacitor.png|text=A normal {{w|capacitor}}.}}
{{circuit-diagram-part|X=577|Y=318|W=96|H=62|image=circuit_diagram-577-318-096-062-magic.png|text="{{w|Magic Smoke}}" is the legendary stuff that all circuit components require to function. This is why all components cease to function after releasing smoke.{{Citation needed}} }}
{{circuit-diagram-part|X=669|Y=315|W=51|H=66|image=circuit_diagram-669-315-051-066-frayed-wires.png|text=Some frayed or dangling wires. The wire on the left seems confused because it did not manage to cross with the one on the right.}}
{{circuit-diagram-part|X=567|Y=392|W=58|H=48|image=circuit_diagram-567-392-058-048-buoy.png|text=An object which is either a {{w|Fishing float|float}} used in fishing, a {{w|Tippe top}}, or perhaps a {{w|Naval mine|mine}}.}}
{{circuit-diagram-part|X=458|Y=336|W=111|H=86|image=circuit_diagram-458-336-111-086-moral-rectifier.png|text=A {{w|Diode_bridge|bridge rectifier}}, which would normally turn alternating current at the top and bottom into direct current on the left and right. In this case, it is labeled as a "moral rectifier". This is presumably a play on the idea of moral rectitude – it makes your circuit more moral. Why this matters in a circuit is unclear.}}
{{circuit-diagram-part|X=423|Y=259|W=80|H=85|image=circuit_diagram-423-259-080-085-warm-front.png|text=This resembles both the schematic symbol for part of a {{w|transformer}} and the meteorological symbol for a warm front. A {{w|warm front}} is a feature on a {{w|Surface weather analysis|synoptic weather map}}.}}
{{circuit-diagram-part|X=190|Y=199|W=54|H=52|image=circuit_diagram-190-199-054-052-battery.png|text=A normal 50-volt battery.}}
{{circuit-diagram-part|X=173|Y=200|W=89|H=56|image=circuit_diagram-173-200-089-056-shorted-battery.png|text=A battery is grounded on both sides. Something will melt or burn out quickly, unless these are separate "earth ground"s, in which case the ground might get a bit cooked.}}
{{circuit-diagram-part|X=259|Y=198|W=174|H=25|image=circuit_diagram-259-198-174-025-pull-wire.png|text=Text reads "Pull this wire really tight". This kind of physical-property issue may indicate a high-frequency radio device. Or, given the absurdity of the context, it's a silly reference to a "high tension wire."}}
{{circuit-diagram-part|X=141|Y=211|W=41|H=91|image=circuit_diagram-141-211-041-091-3-8-inch.png|text=A specified 3/8-inch separation. This probably indicates a carefully controlled capacitance issue. Also contradicts the scale of the drawing, by which the distance shown would be about 0.8 miles or 0.8 km.}}
{{circuit-diagram-part|X=173|Y=309|W=92|H=59|image=circuit_diagram-173-309-092-059-eel.png|text=An {{w|electric eel}}. This may be an effective power source in the circuit, capable of producing a shock at up to 600 volts and 1 ampere of current (600 watts), but for less than 2 ms.}}
{{circuit-diagram-part|X=266|Y=307|W=35|H=41|image=circuit_diagram-266-307-035-041-resistor.png|text=A normal resistor.}}
{{circuit-diagram-part|X=222|Y=358|W=34|H=29|image=circuit_diagram-222-358-034-029-capacitor.png|text=A normal capacitor.}}
{{circuit-diagram-part|X=130|Y=335|W=44|H=40|image=circuit_diagram-130-335-044-040-resistor.png|text=A normal resistor, labeled "ë". This may be a play on {{w|e (mathematical constant)|Euler's Number}}, which doesn't normally have a {{w|tréma}} or an {{w|umlaut (linguistics)|umlaut}}. Alternatively instead of being an umlaut or tréma it may indicate the second {{w|derivative}} of e with respect to time in {{w|Newton's notation}}, in which case, as e is a constant, the resistance of this element is zero.}}
{{circuit-diagram-part|X=65|Y=249|W=61|H=92|image=circuit_diagram-065-249-061-092-blender.png|text=Our best guess is that this is a {{w|blender}}. Due to the scale, this would certainly be the worlds largest blender. Record setting blenders are not typically part of computer circuits{{Citation needed}}}}
{{circuit-diagram-part|X=20|Y=342|W=115|H=73|image=circuit_diagram-020-342-115-073-arduino.png|text=An {{w|arduino}}, labeled "Arduino, just for blog cred". May refer to the fact that inexpensive, easy-to-integrate single-board computers like the arduino, which have contributed to the rise of {{w|Maker culture}}, are used and discussed frequently in that culture, and the use of one might impress readers. The comment implies that an arduino is not otherwise needed in this circuit, although it is necessarily hard to tell, given the other components of the circuit.}}
{{circuit-diagram-part|X=39|Y=423|W=118|H=82|image=circuit_diagram-039-423-118-082-meca.png|text=A chip labeled "Most expensive chip available". The small curve at the top is a part of the packaging designed to show its orientation.}}
{{circuit-diagram-part|X=159|Y=428|W=91|H=50|image=circuit_diagram-159-428-091-050-neck-strap.png|text=Labeled "Neck Strap". Perhaps a piece of torture equipment or indicating that the circuit is part of an {{w|electric chair}}? May also be a reference to the grounded wrist straps people working with electronics commonly wear, to prevent accidental static discharges from frying the circuitry.}}
{{circuit-diagram-part|X=147|Y=480|W=110|H=88|image=circuit_diagram-147-480-110-088-switch.png|text=A switch labeled "Hire someone to open and close switch real fast." Possibly meant to perform the function of an {{w|Electronic oscillator|oscillator}} in a more hackish manner and the reason for the neck strap. Could also be a reference to {{w|Maxwell's Demon}}.}}
{{circuit-diagram-part|X=273|Y=498|W=61|H=64|image=circuit_diagram-273-498-061-064-resistor.png|text=A 5 ohm resistor labeled "(decoy)". One end is not attached to anything. Perhaps this indicates wishful thinking that electrons might be tricked into entering this part of the circuit despite the fact that there's nowhere for them to go?}}
{{circuit-diagram-part|X=307|Y=453|W=103|H=56|image=circuit_diagram-307-453-103-056-tongue.png|text=A pair of contacts, labeled "Touch Tongue Here". Could be referring to the practice of daring someone to touch their tongue to the contacts of a 9V battery.}}
{{circuit-diagram-part|X=301|Y=270|W=45|H=45|image=circuit_diagram-301-270-045-045-frown.png|text=A frowny-face. See the float/mine.}}
{{circuit-diagram-part|X=294|Y=311|W=128|H=124|image=circuit_diagram-294-311-128-124-IC.png|text=A small integrated circuit. The lower gate is an {{w|Inverter (logic gate)|inverter}}, wired as a free-running oscillator. The upper gate is an {{w|XOR gate|XOR}} wired to act as either a free-running oscillator or a latch. Since the XOR will be slower than the inverter, the overall output of the upper gate is probably very chaotic. Two "input" wires are not connected at all. An additional wire is attached to the top with hot glue. This last wire probably acts to control static electricity and leakage.}}
{{circuit-diagram-part|X=302|Y=235|W=91|H=25|image=circuit_diagram-302-235-091-025-curve.png|text=A caution sign at a curve. Another road feature in the circuit. This is a play on the notion that 90-degree corners on printed circuit board traces can disrupt signal integrity.}}
{{circuit-diagram-part|X=401|Y=455|W=67|H=68|image=circuit_diagram-401-455-067-068-CH3.png|text=A {{w|methyl group}} (chemistry) attached to a corner. If the circuit were an organic chemical, it would be reasonable to find a number of these.}}
{{circuit-diagram-part|X=453|Y=167|W=43|H=93|image=circuit_diagram-453-167-043-093-baloon.png|text=A balloon, possibly blowing in a breeze.}}
{{circuit-diagram-part|X=572|Y=68|W=22|H=43|image=circuit_diagram-572-068-022-043-inductor.png|text=A coil or inductor.}}
{{circuit-diagram-part|X=508|Y=96|W=42|H=20|image=circuit_diagram-508-096-042-020-inductor.png|text=A coil or inductor.}}
{{circuit-diagram-part|X=534|Y=61|W=22|H=31|image=circuit_diagram-534-061-022-031-ground.png|text=A ground connection.}}
{{circuit-diagram-part|X=472|Y=49|W=134|H=140|image=circuit_diagram-472-049-134-140-solderr-blob.png|text=A {{w|Soldering#Soldering_defects|solder blob}} covering a portion of the circuit. Normally, this would not be part of the circuit diagram, but a mistake in building the circuit.}}
{{circuit-diagram-part|X=493|Y=443|W=207|H=158|image=circuit_diagram-493-443-207-158-res-rats-nest.png|text=A rat's nest of 1 ohm resistors. It is labeled "Oh, so you think you're such a whiz at EE201?" The name EE201 (Electrical Engineering 201) follows US course naming conventions for what appears to be a basic level course in electrical engineering (compare the term {{w|101 (term)|101}}), which would include being taught how to [http://www.wikihow.com/Calculate-Series-and-Parallel-Resistance calculate the effective resistance of various resistor networks]. Performing the calculation on a network this complex would probably be very difficult. Experimentally, the resistance of the mass can be measured as, likely coincidentally, about π/4.
A grid of 1 ohm resistors has appeared earlier in [[356: Nerd Sniping]], a comic also referred to in the title text.}}
{{circuit-diagram-part|X=315|Y=533|W=232|H=200|image=circuit_diagram-362-531-151-167-arena.png|text=An {{w|arena}}, with a few bodies in it. Note the direction of movement enforced by the surrounding diodes, {{w|Mad_Max_Beyond_Thunderdome|"two men enter, one man leaves"}}, a film reference.}}
{{circuit-diagram-part|X=569|Y=653|W=47|H=51|image=circuit_diagram-569-653-047-051-resistor.png|text=A "{{w|pi}}" ohm resistor.}}
{{circuit-diagram-part|X=610|Y=655|W=75|H=70|image=circuit_diagram-610-655-075-070-generator.png|text=A 500-volt AC generator. The wiring to the right shorts out this generator.}}
{{circuit-diagram-part|X=481|Y=682|W=85|H=64|image=circuit_diagram-481-682-085-064-ground.png|text=A ground connection, labeled "Bury deep, but not too deep". This type of ground connection is called an "earth ground" The "too deep" part might be a reference to {{w|Moria (Middle-earth)|Moria}} in Lord of Rings. The dwarves dug too deeply and disturbed a Balrog. See also comic [[760]].}}
{{circuit-diagram-part|X=17|Y=610|W=75|H=73|image=circuit_diagram-017-610-075-073-fishhook.png|text=A ground connection at the end of a curve, looking like a fishhook. Means perhaps "earthed down under", i.e., Australia or the southern hemisphere.}}
{{circuit-diagram-part|X=206|Y=662|W=66|H=45|image=circuit_diagram-206-662-066-045-yarn.png|text=A length of "wire" is labeled "yarn". This probably makes it a terrible conductor.}}
{{circuit-diagram-part|X=102|Y=590|W=93|H=88|image=circuit_diagram-102-590-093-088-fluxcapacitor.png|text=The {{w|DeLorean time machine#Flux capacitor|flux capacitor}} from {{w|Back to the Future}}. This may be difficult to implement, since flux capacitors are not available to most people{{Citation needed}},}}
{{circuit-diagram-part|X=138|Y=685|W=54|H=24|image=circuit_diagram-138-685-054-024-I95.png|text=A road sign for "I-95". {{w|Interstate 95}} is the main north-south highway on the east coast of the United States, running from Maine to Florida.}}
{{circuit-diagram-part|X=12|Y=713|W=134|H=36|image=circuit_diagram-012-713-134-036-tothesun.png|text=A connection labeled "To center of Sun". A 93-million-mile or 150-million-km circuit is rather large{{Citation needed}}.}}
{{circuit-diagram-part|X=31|Y=753|W=144|H=177|image=circuit_diagram-031-753-144-177-rats-nest.png|text=A rat's nest of wires. Everything winds up being connected. May also be a parody diagram of an [http://i.stack.imgur.com/np2p9.png undirected graph], from graph theory.}}
{{circuit-diagram-part|X=22|Y=513|W=97|H=61|image=circuit_diagram-022-513-097-061-esf.png|text=A label reading "Electrons Single File". If this happens, the resistance in this section of wire would be rather high.}}
{{circuit-diagram-part|X=256|Y=619|W=29|H=39|image=circuit_diagram-256-619-029-039-ground.png|text=A ground connection.}}
{{circuit-diagram-part|X=589|Y=600|W=58|H=46|image=circuit_diagram-589-600-058-046-vibrator.png|text=A vibrator, which would be a motor with an off-center weight attached to it.}}
{{circuit-diagram-part|X=532|Y=779|W=74|H=52|image=circuit_diagram-532-779-074-052-motor.png|text=A motor, labeled "To Scale". This indicates that the physical size and shape of the motor must match the size of the parts around it, or is consistent with the specified scale of the drawing. }}
{{circuit-diagram-part|X=662|Y=822|W=73|H=109|image=circuit_diagram-662-822-073-109-holy-ground.png|text=A ground connection, in a beaker labeled "{{w|Holy Water}}", possibly creating {{w|Holy ground (religion)|holy ground}}.}}
{{circuit-diagram-part|X=197|Y=740|W=48|H=55|image=circuit_diagram-197-740-048-055-speed.png|text=A sign indicating a speed limit of 55 MPH. This is a rather typical road sign, but inappropriate for a circuit diagram. It is presumably referring to the speed of individual electrons, which can normally vary up to almost the speed of light - although based on the width of the wire and assuming about 1A of current, the ''average'' speed of all electrons, the drift velocity, is likely to be in the order of 10<sup>-17</sup>mph.}}
{{circuit-diagram-part|X=238|Y=706|W=100|H=116|image=circuit_diagram-238-706-100-116-flipflop.png|text=A pair of {{w|NOR gate}}s wired as a SR (set-reset) {{w|Flip-flop (electronics)|flip-flop}}. The label reads "May use an actual sandal instead", which is a play on the meanings of the term "{{w|Flip-flops|flip-flop}}".}}
{{circuit-diagram-part|X=322|Y=708|W=70|H=54|image=circuit_diagram-322-708-070-054-holdingpen.png|text=Something that could be the side view of a fence, labeled "Holding Pen".}}
{{circuit-diagram-part|X=339|Y=777|W=42|H=49|image=circuit_diagram-339-777-042-049-knot.png|text=A simple {{w|overhand knot}}. Also looks like a pretzel, which would have pretty high resistance.}}
{{circuit-diagram-part|X=191|Y=889|W=149|H=33|image=circuit_diagram-191-889-149-033-ecg.png|text=This appears to be an {{w|Electrocardiography|electrocardiograph}} (ECG) trace, but not the sort that would be seen in a healthy person. If this were a real ECG trace, the absence of large, clear {{w|P wave (electrocardiography)|P waves}} might indicate {{w|Atrial Fibrillation|fine atrial fibrillation}}, but in some recording configurations, P waves are sometimes lost in the noise anyway. Additionally, without a time scale to tell us the ventricular heart rate, it is impossible to make a strong educated diagnosis of any hypothetical disease at all. If we assume it is atrial fibrillation, is not clear if Randall intended this, or if he is just not familiar with how a normal ECG should look. Lastly, it does not appear that this is an actual ECG machine, but simply a bent wire, much like the "Not a resistor" label nearby.}}
{{circuit-diagram-part|X=223|Y=826|W=82|H=68|image=circuit_diagram-223-826-082-068-photodiode.png|text=A {{w|photodiode}}, labeled "Tear Collector". A photodiode is a light-sensing device.}}
{{circuit-diagram-part|X=373|Y=859|W=49|H=68|image=circuit_diagram-373-859-049-068-lamp.png|text=A lamp. This is not [http://electronicsclub.info/circuitsymbols.htm the symbol used in electrical circuits], but a drawing of a lightbulb.}}
{{circuit-diagram-part|X=450|Y=887|W=65|H=32|image=circuit_diagram-450-887-065-032-inductor.png|text=A coil or inductor.}}
{{circuit-diagram-part|X=537|Y=847|W=120|H=72|image=circuit_diagram-537-847-120-072-inductor.png|text=A coil or inductor, labeled "Take off shirt while wiring this part. Ooh, yeah, I like that."}}
{{circuit-diagram-part|X=504|Y=860|W=34|H=41|image=circuit_diagram-504-860-034-041-resistor.png|text=A resistor labeled "?". Presumably this means the resistance is unknown.}}
{{circuit-diagram-part|X=459|Y=828|W=55|H=38|image=circuit_diagram-459-828-055-038-resistor.png|text=A resistor labeled "YES". Likely another improper unit - a reference to boolean values YES (TRUE) and NO (FALSE). Depending on the limits of a circuit, a resistor would still have a YES boolean value. Possibly indicating that this is a real resistor, as opposed to the one above it in the circuit, labeled "not a resistor." This may also be a reference to the question: "How much INSERT OBJECT HERE do you want?, Yes."}}
{{circuit-diagram-part|X=389|Y=774|W=58|H=53|image=circuit_diagram-389-774-058-053-resistor.png|text=A resistor labeled "8 mm". Resistance is measured in ohms, so 8 millimeters seems nonsensical.}}
{{circuit-diagram-part|X=443|Y=747|W=93|H=84|image=circuit_diagram-443-747-093-084-resistor.png|text=A resistor labeled "Not a resistor; wire just does this". Apparently the wire is or must be physically bent into a zig-zag shape, which would not serve much useful purpose in a low frequency or DC circuit, or perhaps it reflects the fact that any wire has a certain (small) amount of resistance just by being a wire. In a {{w|Radio frequency|high frequency circuit}} this can be actually useful, as the shape and length of the {{w|Transmission line|transmission line}} alters the {{w|Electrical impedance|impedance}} of the line. ([https://commons.wikimedia.org/wiki/File:Phaseshifter2.png Example])}}
{{circuit-diagram-part|X=415|Y=863|W=82|H=24|image=circuit_diagram-415-863-082-024-unsure.png|text=A symbol for a feedthrough capacitor, labeled "3 Liters". Probable word-play on "capacity/capacitor." Also similar to the symbol for an orifice or flow restriction used on plumbing or hydraulic diagrams, in which case the "3 Liters" might mean 3 liters per minute or per second.}}
|}

==Transcript==
:[In the upper left corner there is a map scale, labeled with 1 mi (1 km).]
:[Underneath the scale is a circuit diagram with the following items connected:]
:An antenna symbol.
:A blender.
:An Arduino, labeled with "Arduino, just for blog cred".
:A chip, labeled "Most expensive chip available".
:A symbol for an inductor.
:A pattern that looks like a highway cloverleaf.
:A battery symbol (with the + and - symbols on the wrong ends) with a value of √2V.
:A resistor symbol label "120Ω or to taste".
:A switch that is labeled "glue open".
:A transistor with two emitters, one P and one N, and no collector.
:A jar of scarab beetles.
:A resistor labeled "brown blue orange".
:An unlabeled resistor with a center tap.
:A capacitor.
:A diode.
:A ground.
:An inductor.
:An another inductor.
::The two inductors and ground are all covered by a "solder blob".
:A "666 timer" that has pin 5 going into a question mark.
:A compass rose.
:A battery, labeled 50V, with grounds on both sides.
:A long horizontal wire that is labeled "pull this wire really tight".
:An AC source that is labeled 240V, shorted out, with a label on the short "Omit this if you're a wimp."
:An inductor that is labeled with "11kg".
:A Batman symbol.
:A squirrel.
:A wire that is labeled as a distance 3/8".
:A 50V battery.
:A frowny face.
:A vertical wire with a 90 degree bend labeled "caution".
:A balloon.
:An inductor symbol with a line on the bottom edge labeled as "warm front".
:A resistor labeled "ë".
:An electric eel.
:A capacitor.
:An unlabeled resistor.
:A gob of hot glue attached to a chip with an inverter hooked to an XOR gate, both with feedback into each other.
:A neck strap.
:A bridge rectifier labeled as "Moral rectifier".
:A bottle of magic smoke.
:A fishing bobber.
:A broken wire labeled with a question mark.
:A vertical wire labeled with "electrons single file".
:A switch labeled "Hire someone to open and close switch real fast."
:A contact labeled "touch tongue here".
:A resistor labeled "5Ω (decoy)" with only one terminal connected.
:A methyl group attached to a wire.
:A complex mesh of 1Ω resistors labeled with "Oh, so you think you're such a whiz at EE201?"
:A wire labeled "electrons single file".
:A wire bent in a U shape with an upside-down ground on the end.
:A flux capacitor with the bottom wire labeled "I-95".
:A wire labeled "yarn".
:An arena with two diodes going in and one leaving.
:An anode labeled "Bury deep, but not too deep."
:A motor labeled "vibrator".
:A resistor with a value of π.
:A 500V AC source.
:A wire that leads out of frame with a label "to center of sun".
:A 55 MPH speed limit sign.
:An SR latch (flip-flop) labeled "may use an actual sandal instead".
:A holding pen.
:A wire in a knot.
:A resistor labeled "8mm".
:A resistor symbol labeled "not a resistor; wire just does this".
:A motor symbol labeled "to scale".
:A tangled mess of wires connected and jumping over each other.
:A photo diode labeled "tear collector".
:A wire in the shape of a ECG.
:A light bulb.
:A capacitor-looking symbol labeled "3 liters".
:A resistor labeled "yes".
:An unlabeled inductor.
:A resistor with a question mark as a label.
:An inductor labeled "Take off shirt while wiring this part. Ooh, yeah, I like that."
:A ground symbol immersed in a beaker of holy water.

==Trivia==

*This is one of the [[:Category:Footer comics|six footer comics]] linked at the bottom part of the {{xkcd}} website.

{{comic discussion}}
[[Category:Physics]]
[[Category:Maps]]
[[Category:Footer comics]]
[[Category:Squirrels]]
[[Category:Back to the Future]]