primary cache
(L1 cache, level one cache) A small, fast cache memory inside or close to the CPU chip.
For example, an Intel 80486 has an eight-kilobyte on-chip cache, and most Pentiums have a 16-KB on-chip level one cache that consists of an 8-KB instruction cache and an 8-KB data cache. The larger, slower secondary cache is normally connected to the CPU via its external bus.Last updated: 1997-06-25
Primary Domain Controller
(PDC) Each Windows NT domain has a Primary Domain Controller and zero or more Backup Domain Controllers. The PDC holds the SAM database and authenticates access requests from workstations and servers in the domain.
Last updated: 2003-07-16
primary key
<database>
A unique identifier, often an integer, that labels a certain row in a table of a relational database.
When this value occurs in other tables as a reference to a particular row in the first table it is called a "foreign key". Some RDBMSes can generate a new unique identifier each time a new row is inserted, others merely allow a column to be constrained to contain unique values. A table may have multiple candidate keys, from which the primary key is chosen. The primary key should be an arbitrary value, such as an autoincrementing integer. This avoids dependence on uniqueness, permanence and format of existing columns with real-world meaning (e.g. a person's name) or other external identifier (e.g. social security number). There should be enough possible primary key values to cater for the current and expected number of rows, bearing in mind that a wider column will generally be slower to process.Last updated: 2006-05-29
primary management domain
(PRMD) The component of an X.400 electronic mail address that gives the organisation name, usually abbreviated to p= in written addresses.
See also ADMD.Last updated: 2003-05-15
Primary Rate Interface
(PRI) A type of ISDN connection. In North America and Japan, this consists of 24 channels, usually divided into 23 B channels and 1 D channel, and runs over the same physical interface as T1. Elsewhere the PRI has 31 user channels, usually divided into 30 B channels and 1 D channel and is based on the E1 interface. PRI is typically used for connections such as one between a PBX (private branch exchange, a telephone exchange operated by the customer of a telephone company) and a CO (central office, of the telephone company) or IXC (inter exchange carrier, a long distance telephone company).Last updated: 1995-01-18
primary storage
main memoryPrime Computer
<company>
(Or "Pr1ME") A minicomputer manufacturer.
[Dates? Status? Products? Addresses?]Last updated: 1996-09-28
Primenet, Inc.
Arizona's Internet provider.Last updated: 1994-12-08
prime number theorem
The number of prime numbers less than x is about x/log(x). Here "is about" means that the ratio of the two things tends to 1 as x tends to infinity. This was first conjectured by Gauss in the early 19th century, and was proved (independently) by Hadamard and de la Vall'ee Poussin in 1896. Their proofs relied on complex analysis, but Erdös and Selberg later found an "elementary" proof.
Last updated: 1995-04-10
prime time
(From TV programming) Normal high-usage hours on a time-sharing system; the day shift. Avoidance of prime time was traditionally given as a major reason for night mode hacking. The rise of the personal workstation has rendered this term, along with time-sharing itself, almost obsolete. The hackish tendency to late-night hacking runs has changed not a bit. [Jargon File]Last updated: 1995-01-18
primitive
A function, operator, or type which is built into a programming language (or operating system), either for speed of execution or because it would be impossible to write it in the language. Primitives typically include the arithmetic and logical operations (plus, minus, and, or, etc.) and are implemented by a small number of machine language instructions.
Last updated: 1995-05-01
Nearby terms:
preventive maintenance ♦ PRI ♦ primary cache ♦ Primary Domain Controller ♦ primary key
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