A register is an electronic device that holds a binary number. One can be constructed from a bank of flip-flops arranged in a parallel load or serial load configuration, or both. Similarly, a register may be read from in parallel or serial, or both. An example of a simple 4-bit parallel in/parallel out register is shown here:
    Assembly:            Whole Unit:
      +---+                 +-+   
I3----|D Q|--O3             | |
    +-|>  |           I--/--|C|--/--O
    | +---+              4  | |  4
    | +---+                 | |
I2--|-|D Q|--O2             +-+
    +-|>  |
    | +---+
    | +---+
I1--|-|D Q|--O1
    +-|>  |
    | +---+
    | +---+
I0--|-|D Q|--O0
clk-+-|>  |

The 'C' in the Whole Unit diagram is simply a name for this register and the '4' indicates that there is a 4-bit bus on both the input and output.

See also shift register (for a serial load configuration), accumulator, three-state logic, arithmetic logic unit, sequential arithmetic, D Flip-Flop, SR Flip-Flop, JK Flip-Flop.

The register keyword of C (and C++) recommends to the compiler that a simple variable be stored in a machine register, if possible. As such, it has an immediate syntactic effect: it is illegal to take the address of a register variable using the & operator. This is the only effect required of a C compiler!

Generally, the compiler (and especially the optimiser) know better than you which variables should be placed in a register. The optimizer is your friend. Most authorities therefore advise against declaring your variables register. However, when performing micro-optimisations for a specific compiler on a specific platform, it might be a good idea to try this keyword (especially if the generated assembly language is not to your liking). As always, you must perform careful testing to see if adding the keyword makes matters better or worse.

Refers to special locations inside the core of a micro(processor|controller). These can be thought of as memory locations, but they are so much more.


These suckers can be accessed within the same clock cycle they are being used. Usually you have to go out to main memory, pluck the value from there, operate on it, and then put it somewhere. This can take forever! But write something to a register - BAM! It's there! Increment it - BAM! it's incremented. Some processors can operate on multiple registers in one machine cycle. Yowza!

These are used for ultra-tight and precise loops and algorithms, and are a basic way of passing information from one function to another. Part of a processor's bit rating (ie, a 32 bit processor) is determined by how large these registers are. You could have a 32 bit core, but if your registers are all 8bit then many people consider the processor to be an 8 bit (and, for all intents and purposes, it is as effective as an 8 bit)

Most people don't even think about the registers anymore. The OS or the compiler determines how they get used, and that's the end of it - which is ok, since you'll rarely run across someone who programs in a low enough language who touches the registers.

In linguistics, the "level" of formality of an utterance or text. In general, something like five levels will be identified (here from "highest" to "lowest"):

  • Ceremonial language: ossified formulations, which may well use archaic grammatical and lexical forms, and which is used on specific occasions, often repeated by rote. "I, the undersigned, being of sound mind and body, do hereby call upon the person or persons duly appointed to secure the portal."
  • Formal discourse: freely chosen language which complies fairly carefully to traditional grammatical standards or at least to the speaker's idea of them; lexical choices may tend towards the pedantic, learned, pompous or frilly. Most of this writeup, for example, or an academic lecture. "I would be most grateful if you could shut the door".
  • 'Neutral', unmarked speech or writing; a somewhat chimerical concept. Normal speech is rarely perfectly grammatical; indeed, if transcribed it generally looks like gibberish. It relies heavily on intonation and extraverbal reference, and contains a high degree of redundant information. Neutral written language, if it existed, would avoid both colloquial forms (eg in English, contracted forms like I'd, should've1; in other European languages the use of familiar pronouns like tu, du, jij, vôce) as well as excessive floweriness; would probably not worry overmuch about compliance with the niceties of prescriptive grammar (such as split infinitives or the less/fewer distinction in English), whilst complying with the underlying syntactical structures of the language. "Please shut the door".
  • Colloquial speech or writing: discourse where specific grammatical, lexical and pragmatic forms are used to indicate that the situation is informal, but where the vast majority of the semantic content is explicitly included. Lexical items which would be shunned in higher registers for one reason or another may well be included. The underlying syntactic structures still apply, but spoken forms will generally be extremely fragmentary. "Can you shut the door, mate?"
  • Familiar speech (rarely written). Speech where the level of intimacy between the participants is (or is assumed to be by the git who is effing and blinding at you) such that a high proportion of the semantic content can be omitted or referred to only implicitly or elliptically. "Born in a fucking barn, were we?"

There are clearly a number of sociolinguistic factors which determine how any given utterance may be intended or received; it is of course more of a continuum than a set of discrete levels.

Register errors - using "inappropriate" levels of language, producing an utterance which is likely to be taken as either pompous, rude, or just plain weird - are an issue in various linguistic fields; they are a common problem for language learners. An anglophone learner of Italian may find the uninflected "cui" construction (for "which") easier to use than the alternative gender-inflected "il quale/la quale/i quali/le quali" form, but the former is in fact rather high-flown for normal speech; conversely, Italians learning English are likely to overuse Latin-root cognates of their familiar Italian verbs rather than the Germanic-rooted prepositional and phrasal verbs which sound "simpler" to English speaker's ears ("establish" or "construct" rather than "set up", for example).

1. These contracted forms in written English represent elision and articulation which occurs in all but the most formal registers of speech, but they are generally considered to be markers of a fairly colloquial register if they are used in writing, particularly outside direct speech. By contrast many similar phenomena in other spoken European languages are formalised into the writing system and used for all registers (e.g. Italian della = di + la, German zum = zu + dem, Portuguese á = a + a ) or a wider range (e.g. Dutch m'n, z'n for unstressed mijn, zijn).

Reg"is*ter (rej"is*tər), n. [OE. registre, F. registre, LL. registrum,regestum, L. regesta, pl., fr. regerere, regestum, to carry back, to register; pref. re- re- + gerere to carry. See Jest, and cf. Regest.]


A written account or entry; an official or formal enumeration, description, or record; a memorial record; a list or roll; a schedule.

As you have one eye upon my follies, . . . turn another into the register of your own.

2. (Com.)


A record containing a list and description of the merchant vessels belonging to a port or customs district.


A certificate issued by the collector of customs of a port or district to the owner of a vessel, containing the description of a vessel, its name, ownership, and other material facts. It is kept on board the vessel, to be used as an evidence of nationality or as a muniment of title.

3. [Cf. LL. registrarius. Cf. Regisrar.]

One who registers or records; a registrar; a recorder; especially, a public officer charged with the duty of recording certain transactions or events; as, a register of deeds.


That which registers or records. Specifically:

(a) (Mech.)

A contrivance for automatically noting the performance of a machine or the rapidity of a process.

(b) (Teleg.)

The part of a telegraphic apparatus which records automatically the message received.


A machine for registering automatically the number of persons passing through a gateway, fares taken, etc.; a telltale.


A lid, stopper, or sliding plate, in a furnace, stove, etc., for regulating the admission of air to the fuel; also, an arrangement containing dampers or shutters, as in the floor or wall of a room or passage, or in a chimney, for admitting or excluding heated air, or for regulating ventilation.

6. (Print.)


The inner part of the mold in which types are cast.


The correspondence of pages, columns, or lines on the opposite or reverse sides of the sheet.


The correspondence or adjustment of the several impressions in a design which is printed in parts, as in chromolithographic printing, or in the manufacture of paper hangings. See Register, v. i. 2.

7. (Mus.)


The compass of a voice or instrument; a specified portion of the compass of a voice, or a series of vocal tones of a given compass; as, the upper, middle, or lower register; the soprano register; the tenor register.

⇒ In respect to the vocal tones, the thick register properly extends below from the F on the lower space of the treble staff. The thin register extends an octave above this. The small register is above the thin. The voice in the thick register is called the chest voice; in the thin, the head voice. Falsetto is a kind off voice, of a thin, shrull quality, made by using the mechanism of the upper thin register for tones below the proper limit on the scale. E. Behnke.


A stop or set of pipes in an organ.

Parish register, A book in which are recorded the births, baptisms, marriages, deaths, and burials in a parish.

Syn. -- List; catalogue; roll; record; archives; chronicle; annals. See List.


© Webster 1913

Reg"is*ter (rej"is*tər), v. t. [imp. & p. p. Registered (- tərd); p. pr. & vb. n. Registering.] [Cf. F. regisrer, exregistrer, LL. registrare. See Register, n.]


To enter in a register; to record formally and distinctly, as for future use or service.


To enroll; to enter in a list.

Such follow him as shall be registered.

Registered letter, a letter, the address of which is, on payment of a special fee, registered in the post office and the transmission and delivery of which are attended to with particular care.


© Webster 1913

Reg"is*ter, v. i.


To enroll one's name in a register.

2. (Print.)

To correspond in relative position; as, two pages, columns, etc. , register when the corresponding parts fall in the same line, or when line falls exactly upon line in reverse pages, or (as in chromatic printing) where the various colors of the design are printed consecutively, and perfect adjustment of parts is necessary.


© Webster 1913

Reg"is*ter (?), v. t. (Securities)

To enter the name of the owner of (a share of stock, a bond, or other security) in a register, or record book. A registered security is transferable only on the written assignment of the owner of record and on surrender of his bond, stock certificate, or the like.


© Webster 1913

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