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(1) In programming, a variable that is used to keep track of anything that must be counted. The programming language determines the number of counters (variables) that are available to a programmer.

(2) In electronics, a circuit that counts pulses and generates an output at a specified time.

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adjective

Diametrically opposed: antipodal, antipodean, antithetical, antonymic, antonymous, contradictory, contrary, converse, diametric, diametrical, opposing, opposite, polar, reverse. See support/oppose.

noun

That which is diametrically opposed to another: antipode, antipodes, antithesis, antonym, contrary, converse, opposite, reverse. Logic contradictory, contrapositive,, support/oppose.

verb

1. To return like for like, especially to return an unfriendly or hostile action with a similar one: hit back, reciprocate, retaliate, retort, strike back. See attack/defend, forgiveness/vindictiveness.
2. To place in opposition or be in opposition to: match, oppose, pit, play off. Idioms: bump heads with, meet head-on, setbeat odds, setbeat someone's throat, tradeblowspunches. See support/oppose.

Definition: opposite, opposing
Antonyms: agreeing, concurring, corresponding, corroborating, equal, same, similar

adv

Definition: contrary, reverse
Antonyms: equally, same, similarly

n. the curved part of the stern of a ship projecting aft above the waterline.

See the Introduction, Abbreviations and Pronunciation for further details.

1. A long horizontal surface used in stores, shops, banks, etc., for display of goods, for work-top areas, or for business transactions.
2. The top or working surface of the base of a kitchen cabinet.

LearnThatWord.com is a free vocabulary and spelling program where you only pay for results!

An instrument or apparatus by which numerical value is computed; in radiology, a device for enumerating ionizing events.

• Coulter c. — see coulter counter.
• Geiger c., Geiger–Müller c. — a radiation counter using a gas-filled tube that indicates the presence of ionizing particles.
• scintillation c. — a device for detecting beta and gamma rays, permitting determination of the concentration of radioisotopes in the body or other substance. It is more important for gamma rays, which are poorly measured by a Geiger counter.

A device for enumerating ionizing events.

• Space Exploration and Rocketry - counter: radiation detection instrument or survey meter
• Parts of Rooms - counter: flat, built-in work surface
• Tables and Desks - counter: level surface over which transactions are conducted or food served, usu. long and narrow
• Parts of Shoes and Accessories - counter: stiffener inserted between liner and outside leather to shape shoe around heel
• Commerce and Trade - counter: long table in store for display of goods
• Opposition, Disagreement, and Attack - counter: (vb) act in opposition

This article is about the term counter used in electronics and computing. For other uses, see Counter (disambiguation).

In digital logic and computing, a counter is a device which stores (and sometimes displays) the number of times a particular event or process has occurred, often in relationship to a clock signal.

Contents 1 Electronic counters 1.1 Asynchronous (ripple) counter 1.2 Synchronous counter 1.3 Decade counter 1.4 Up/down counter 1.5 Ring counter 1.6 Johnson counter 2 Computer science counters 3 Mechanical counters 4 References 5 See also

Electronic counters

In electronics, counters can be implemented quite easily using register-type circuits such as the flip-flop, and a wide variety of classifications exist:

• Asynchronous (ripple) counter – changing state bits are used as clocks to subsequent state flip-flops
• Synchronous counter – all state bits change under control of a single clock
• Decade counter – counts through ten states per stage
• Up/down counter – counts both up and down, under command of a control input
• Ring counter – formed by a shift register with feedback connection in a ring
• Johnson counter – a twisted ring counter
• Cascaded counter

Each is useful for different applications. Usually, counter circuits are digital in nature, and count in natural binary. Many types of counter circuits are available as digital building blocks, for example a number of chips in the 4000 series implement different counters.

Occasionally there are advantages to using a counting sequence other than the natural binary sequence—such as the binary coded decimal counter, a linear feedback shift register counter, or a Gray-code counter.

Counters are useful for digital clocks and timers, and in oven timers, VCR clocks, etc.^[1]

Asynchronous (ripple) counter

Asynchronous counter created from two JK flip-flops

An asynchronous (ripple) counter is a single JK-type flip-flop, with its J (data) input fed from its own inverted output. This circuit can store one bit, and hence can count from zero to one before it overflows (starts over from 0). This counter will increment once for every clock cycle and takes two clock cycles to overflow, so every cycle it will alternate between a transition from 0 to 1 and a transition from 1 to 0. Notice that this creates a new clock with a 50% duty cycle at exactly half the frequency of the input clock. If this output is then used as the clock signal for a similarly arranged D flip-flop (remembering to invert the output to the input), you will get another 1 bit counter that counts half as fast. Putting them together yields a two-bit counter:

Cycle	Q1	Q0	(Q1:Q0)dec
0	0	0	0
1	0	1	1
2	1	0	2
3	1	1	3
4	0	0	0

You can continue to add additional flip-flops, always inverting the output to its own input, and using the output from the previous flip-flop as the clock signal. The result is called a ripple counter, which can count to 2ⁿ − 1 where n is the number of bits (flip-flop stages) in the counter. Ripple counters suffer from unstable outputs as the overflows "Ripple" from stage to stage, but they do find frequent application as dividers for clock signals, where the instantaneous count is unimportant, but the division ratio overall is (to clarify this, a 1-bit counter is exactly equivalent to a divide by two circuit; the output frequency is exactly half that of the input when fed with a regular train of clock pulses).

The use of flip-flop outputs as clocks leads to timing skew between the count data bits, making this ripple technique incompatible with normal synchronous circuit design styles.

Synchronous counter

A 4-bit synchronous counter using JK flip-flops

A simple way of implementing the logic for each bit of an ascending counter (which is what is depicted in the image to the right) is for each bit to toggle when all of the less significant bits are at a logic high state. For example, bit 1 toggles when bit 0 is logic high; bit 2 toggles when both bit 1 and bit 0 are logic high; bit 3 toggles when bit 2, bit 1 and bit 0 are all high; and so on.

Synchronous counters can also be implemented with hardware finite state machines, which are more complex but allow for smoother, more stable transitions.

Hardware-based counters are of this type.

Decade counter

A circuit diagram of decade counter using JK FlipFlops(74LS112D)

A decade counter is one that counts in decimal digits, rather than binary. A decade counter may have each digit binary encoded (that is, it may count in binary-coded decimal, as the 7490 integrated circuit did) or other binary encodings (such as the bi-quinary encoding of the 7490 integrated circuit). Alternatively, it may have a "fully decoded" or one-hot output code in which each output goes high in turn (the 4017 is such a circuit). The latter type of circuit finds applications in multiplexers and demultiplexers, or wherever a scanning type of behavior is useful. Similar counters with different numbers of outputs are also common.

The decade counter is also known as a mod-counter when it counts to ten (0, 1, 2, 3, 4, 5, 6, 7, 8, 9). A Mod Counter that counts to 64 stops at 63 because 0 counts as a valid digit.

Up/down counter

A counter that can change state in either direction, under the control of an up/down selector input, is known as an up/down counter. When the selector is in the up state, the counter increments its value. When the selector is in the down state, the counter decrements the count.

Ring counter

Main article: Ring counter

A ring counter is a circular shift register which is initiated such that only one of its flip-flops is the state one while others are in their zero states.

A ring counter is a Shift Register (a cascade connection of flip-flops) with the output of the last one connected to the input of the first, that is, in a ring. Typically, a pattern consisting of a single bit is circulated so the state repeats every n clock cycles if n flip-flops are used. It can be used as a cycle counter of n states.

Johnson counter

Main article: Ring counter

A Johnson counter (or switchtail ring counter, twisted-ring counter, walking-ring counter, or Moebius counter) is a modified ring counter, where the output from the last stage is inverted and fed back as input to the first stage.^[2][3][4] The register cycles through a sequence of bit-patterns, whose length is equal to twice the length of the shift register, continuing indefinitely. These counters find specialist applications, including those similar to the decade counter, digital-to-analog conversion, etc. They can be implemented easily using D- or JK-type flip-flops.

Computer science counters

Main article: Register machine

In computability theory, a counter is considered a type of memory. A counter stores a single natural number (initially zero) and can be arbitrarily many digits long. A counter is usually considered in conjunction with a finite-state machine (FSM), which can perform the following operations on the counter:

• Check whether the counter is zero
• Increment the counter by one.
• Decrement the counter by one (if it's already zero, this leaves it unchanged).

The following machines are listed in order of power, with each one being strictly more powerful than the one below it:

1. Deterministic or non-deterministic FSM plus two counters
2. Non-deterministic FSM plus one stack
3. Non-deterministic FSM plus one counter
4. Deterministic FSM plus one counter
5. Deterministic or non-deterministic FSM

For the first and last, it doesn't matter whether the FSM is a deterministic finite automaton or a nondeterministic finite automaton. They have equivalent power. The first two and the last one are levels of the Chomsky hierarchy.

The first machine, an FSM plus two counters, is equivalent in power to a Turing machine. See the article on counter machines for a proof.

Mechanical counters

Mechanical counter wheels showing both sides. The bump on the wheel shown at the top engages the ratchet on the wheel below every turn.

Several mechanical counters

Long before electronics became common, mechanical devices were used to count events. These are known as tally counters. They typically consist of a series of disks mounted on an axle, with the digits 0 through 9 marked on their edge. The right most disk moves one increment with each event. Each disk except the left-most has a protrusion that, after the completion of one revolution, moves the next disk to the left one increment. Such counters were originally used to control manufacturing processes, but were later used as odometers for bicycles and cars and in fuel dispensers. One of the largest manufacturers was the Veeder-Root company, and their name was often used for this type of counter.^[5]

Wikimedia Commons has media related to: mechanical counters

References

1. ^ http://www.play-hookey.com/digital/synchronous_counter.html
2. ^ Arun Kumar Singh. Digital Principles Foundation of Circuit Design and Application. New Age Publishers. ISBN 81-224-1759-0. http://books.google.com/books?id=13Wi37h2A-oC&pg=PA113&dq=switchtail+ring+counter+johnson. 
3. ^ Paul Horowitz and Winfield Hill (1989). The Art of Electronics. Cambridge University Press. ISBN 0-521-37095-7. http://books.google.com/books?id=bkOMDgwFA28C&pg=PA667&dq=ring+counter+walking. 
4. ^ Rudolf F. Graf (1999). Modern Dictionary of Electronics. Newnes. ISBN 0-7506-9866-7. http://books.google.com/books?id=uah1PkxWeKYC&pg=PA401&dq=moebius+ring+counter+johnson. 
5. ^ http://www.veeder.com/page/vr_history

See also

• Time to digital converter

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
1.
n. - disk, skranke, bardisk, brik, mønt, forhandlingsobjekt, tæller, partikeltæller, optæller

idioms:

• over the counter    i almindelig handel

2.
v. tr. - modgå, modsige, imødegå
v. intr. - foretage modforanstaltninger, svare igen, slå kontra
adv. - i modsat retning, imod, i strid med
adj. - modsat, kontrol-
n. - bringe, afrundet del af agterspejl på skib, oval, bagkappe

idioms:

• counter espionage    kontraspionage
• counter to    imod

3.
n. - parade, kontrastød, det modsatte

4.
n. - bagkappe

Nederlands (Dutch)
toonbank, balie, bar, teller, fiche, wulf, tegenstoot (b.v. boksen), counter (voetbal), boeg (paard), tegenmaatregel, tegengestelde, tegenargument aanvoeren, zich verzetten tegen, tegenstoot geven, duplicaat-, logenstraffen

Français (French)
1.
n. - guichet, comptoir, bar, zinc, rayon, (Jeux) pion, jeton, compteur

idioms:

• behind the counter    au guichet
• over the counter    au comptoir, sans ordonnance, en vente libre

2.
v. tr. - répondre à, réagir à, s'opposer à, neutraliser, parer (un coup), enrayer (l'inflation)
v. intr. - riposter
adv. - à l'encontre de, contrairement à
adj. - contre (dans les composés)
n. - (Tech) compteur

idioms:

• counter espionage    contre-espionnage
• counter to    contraire à, contradictoire
• go counter    s'opposer à, aller à l'encontre de

3.
n. - caissier

4.
n. - contrefort

Deutsch (German)
1.
n. - Ladentisch, Tresen, Spielmarke

idioms:

• behind the counter    Schalterbeamte, der, Schalterbeamtin, die
• over the counter    über dem Ladentisch (kaufen, verkaufen)

2.
v. - antworten, kontern
adv. - in entgegengesetzter Richtung, (fig) im Widerspruch
adj. - entgegengesetzt
n. - Gegenteil, Konter

idioms:

• counter espionage    Gegenspionage, Spionageabwehr
• counter to    gegen
• go counter    in die falsche Richtung gehen

3.
n. - Zähler

4.
n. - Fersenleder

Ελληνική (Greek)
v. - αντισταθμίζω, εξουδετερώνω, αντιμάχομαι, καταπολεμώ, ανταπαντώ, ανταποδίδω
n. - μετρητής, αριθμητής, καταμετρητής, όργανο μέτρησης, κοντέρ, φίσα, μάρκα (χαρτοπαιξίας κ.λπ.), πάγκος πωλήσεων, θυρίδα ή γκισέ τράπεζας
pref. - αντι-, ανθ(υ)-, διπλο-, επ(ανα)-, ξανα-, παρα-

idioms:

• counter espionage    αντικατασκοπία
• counter to    αντίθετα από, αντίθετος προς, εχθρικός σε
• over the counter    στα φανερά, ανοιχτά, (οικον.) στην εξωχρηματιστηριακή αγορά

Italiano (Italian)
smentire, ribattere, reagire, sportello, contatore, gettone, banco

idioms:

• counter espionage    controspionaggio
• counter to    contrariamente a
• over the counter    in vendita libera, senza bisogno di ricetta medica
• rev counter    contagiri

Português (Portuguese)
v. - opor-se
n. - contador (m), mostrador (m)
pref. - contra

idioms:

• counter espionage    contra-espionagem (f)
• counter to    contrário a
• Geiger counter    contador (m) Geiger
• over the counter    no balcão
• rev counter    contador (m) de revoluções, conta-giros (m) (Téc.)
• under the counter    ilegalmente

Русский (Russian)
противодействовать, парировать, окошко, прилавок, счетчик, фишка

idioms:

• counter espionage    контрразведка
• counter to    вопреки
• Geiger counter    счетчик Гейгера
• over the counter    без рецепта
• rev counter    тахометр
• under the counter    из-под прилавка

Español (Spanish)
1.
n. - ventanilla, taquilla, barra, mostrador

idioms:

• behind the counter    detrás del mostrador
• over the counter    pagar al contado, sin receta, extrabursátil

2.
v. tr. - refutar, rebatir, contrariar, contestar
v. intr. - refutarse, rebatirse, contrariarse, contestarse, medirse
adv. - contrariamente
adj. - contrario, opuesto
n. - ficha, barra, mostrador

idioms:

• counter espionage    contraespionaje
• counter to    contra, contrario a, en contra de, en conflicto con
• go counter    ir contra algo o alguien

3.
n. - contador, medidor

4.
n. - contrafuerte (de un zapato)

Svenska (Swedish)
v. - motsätta sig, bemöta, besvara m schackdrag, kontra
n. - räknare, räkneapparat, spelmark, pjäs, pollett, butiksdisk, expeditionslucka, arbetsbänk (am.), motsats, kontraslag (boxn.), bringa på häst, valv (sjö.), bakkappa på sko
pref. - mot-, kontra-

中文（简体）(Chinese (Simplified))
1. 相反的, 对立的, 反对的, 相反之事物, 回拳, 还击, 对立物, 主跟, 后帮, 反对, 反驳, 反击, 抵消, 反方向地, 相反地

idioms:

• counter espionage    反间谍, 策反
• counter to    相反地

2. 柜台, 筹码, 柜台式长桌, 伪造的硬币

idioms:

• over the counter    不通过交易所直接售给顾客的

3. 计算者, 计算器, 计数器

中文（繁體）(Chinese (Traditional))
1.
n. - 計算者, 計算器, 計數器

2.
n. - 櫃檯, 籌碼, 櫃檯式長桌, 偽造的硬幣

idioms:

• over the counter    不通過交易所直接售給顧客的

3.
adj. - 相反的, 對立的, 反對的
n. - 相反之事物, 回拳, 還擊, 對立物, 主跟, 後幫
v. tr. - 反對, 反駁, 反擊, 抵消
v. intr. - 反對, 反駁, 反擊, 還擊
adv. - 反方向地, 相反地

idioms:

• counter espionage    反間諜, 策反
• counter to    相反地

한국어 (Korean)
1.
n. - 계산대, 카운터, 위조화폐

idioms:

• over the counter    카운터에 돈을 치루다, 증권업자의 가계에서

2.
v. tr. - 대항하다, 무효로 하다, 받아 치다
v. intr. - 받아 치다
adv. - 반대 방향으로, 거꾸로
adj. - 반대의 , 거꾸로의, 짝의
n. - 역 , 반대, 받아 치기

idioms:

• counter to    거스르다

3.
n. - 계산하는 사람, 계산기

4.
n. - 구두의 뒤꿈치 가죽

日本語 (Japanese)
n. - 計算器, 計数器, カウンター, 数取り, 模造硬貨, 取引の材料, 利用されそうな人, 調理台, 逆, かかと革
adj. - 反対の, 命令撤回の, 片方の
v. - 逆に出る, 迎え撃つ
adv. - 反対の方向に

idioms:

• bargaining counter    交渉の場, 特価品売り場
• counter espionage    逆スパイ行為
• counter to    逆らう
• over the counter    店頭で, 小売業者を通じて

العربيه (Arabic)
‏(فعل) رد على, عارض, واجه (الاسم) عداد, طاوله البيع, فيشه قمار (بادئه الكلمه) بادئه تعني عكس أو ضد‏

עברית (Hebrew)
adj. - ‮נגדי, מנוגד, כפול, הפוך‬
n. - ‮צעד נגדי, דבר מנוגד, כיוון הפוך‬
v. tr. - ‮גמל במכה, הגיב, התנגד, אמר דבר מנוגד‬
v. intr. - ‮עשה צעד נגדי‬
adv. - ‮בניגוד, נגד, בכיוון הפוך‬
n. - ‮דלפק, דוכן, מד-, מונה, אסימון-משחק, העתק‬
n. - ‮חלק חזה הסוס שמתחת לצוואר, החלק העקום של ירכתי אוניה, חלק מוקף קווים של אות דפוס‬
n. - ‮הצד האחורי של נעל, סביב העקב‬

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