compact
1. (Or "finite", "isolated") In domain theory, an element d of a cpo D is
compact if and only if, for any chain S, a subset of D,
d <= lub S => there exists s in S such that d <= s.
I.e. you always reach d (or better) after a finite number of steps up the
chain.
("<=" is written in LaTeX as \sqsubseteq).
[Jargon File]
(1995-01-13)
2. Of a design, describes the valuable property that it can all be apprehended
at once in one's head. This generally means the thing created from the design
can be used with greater facility and fewer errors than an equivalent tool that
is not compact. Compactness does not imply triviality or lack of power; for
example, C is compact and Fortran is not, but C is more powerful than Fortran.
Designs become non-compact through accreting features and cruft that don't merge
cleanly into the overall design scheme (thus, some fans of Classic C maintain
that ANSI C is no longer compact).
(1995-01-13)
Nearby terms:
communication system « Community of Massive Gaming
Agency « COMNET « compact » Compact COBOL »
Compact Disc » Compact Disc interactive
Compact COBOL
A subset of COBOL defined, but not published, ca. 1961.
[Sammet 1969, p. 339].
(1995-01-19)
Nearby terms:
Community of Massive Gaming Agency « COMNET «
compact «
Compact COBOL » Compact Disc » Compact Disc
interactive » Compact Disc Read-Only Memory
Compact Disc
<storage> (CD) (Not "disk", this spelling is part of the standard).
A 4.72 inch disc developed by Sony and Philips that can store, on the same disc,
still and/or moving images in monochrome and/or color; stereo or two separate
sound tracks integrated with and/or separate from the images; and digital
program and information files.
The same fabrication process is used to make both audio CDs and CD-ROMs for
storing computer data, the only difference is in the device used to read the CD
(the player or drive).
CD Information Center.
(1999-06-23)
Nearby terms:
COMNET « compact « Compact COBOL « Compact Disc
» Compact Disc interactive » Compact Disc Read-Only
Memory » Compact Disc Read-Write
Compact Disc interactive
(CD-i) An embedded application of CD-ROM allowing the user limited interaction
with films, games and educational applications via a special controller.
(1994-11-02)
Nearby terms:
compact « Compact COBOL « Compact Disc « Compact
Disc interactive » Compact Disc Read-Only Memory
» Compact Disc Read-Write » Compact Disc Recordable
Compact Disc Read-Only Memory
<storage> (CD-ROM) A non-volatile optical data storage medium using the
same physical format as audio compact discs, readable by a computer with a
CD-ROM drive.
CD-ROM is popular for distribution of large databases, software and especially
multimedia applications. The maximum capacity is about 600 megabytes. A CD can
store around 640 megabytes of data - about 12 billion bytes per pound weight.
CD-ROM drives are rated with a speed factor relative to music CDs (1x or 1-speed
which gives a data transfer rate of 150 kilobytes per second). 12x drives were
common in April 1997. Above 12x speed, there are problems with vibration and
heat. Constant angular velocity (CAV) drives give speeds up to 20x but due to
the nature of CAV the actual throughput increase over 12x is less than 20/12.
20x was thought to be the maximum speed due to mechanical constraints but on
1998-02-24, Samsung Electronics introduced the SCR-3230, a 32x CD-ROM drive
which uses a ball bearing system to balance the spinning CD-ROM in the drive to
reduce noise.
CD-ROM drives may connect to an IDE interface, a SCSI interface or a propritary
interface, of which there are three - Sony, Panasonic, and Mitsumi. Most CD-ROM
drives can also play audio CDs.
There are several formats used for CD-ROM data, including Green Book CD-ROM,
White Book CD-ROM and Yellow Book CD-ROM. ISO 9660 defines a standard file
system, later extended by Joliet.
See also Compact Disc Recordable, Digital Versatile Disc.
Byte, February 1997.
(2006-09-25)
Nearby terms:
Compact COBOL « Compact Disc « Compact Disc
interactive «
Compact Disc Read-Only Memory » Compact Disc
Read-Write » Compact Disc Recordable » Compact Disc
Rewritable
Compact Disc Read-Write
Compact Disc Rewritable
Nearby terms:
Compact Disc « Compact Disc interactive « Compact
Disc Read-Only Memory « Compact Disc Read-Write
» Compact Disc Recordable » Compact Disc Rewritable
» compaction
Compact Disc Recordable
<storage> (CD-R) A write-once version of CD-ROM. CD-Rs can hold about 650
megabytes of data. They are very durable and can be read by normal CD-ROM
drives, but once data has been written it cannot be altered.
Standard prerecorded CDs have their information permanently stamped into an
aluminium reflecting layer. CD-R discs have a dye-based recording layer and an
additional golden reflecting layer.
Digital information is written to the disc by burning (forming) pits in the
recording layer in a pattern corresponding to that of a conventional CD.
The laser beam heats the substrate and recording layer to approximately 250 C.
The recording layer melts and the substrate expands into the space that becomes
available.
Phillips: New Technologies.
See also CD-RW and DVD-RAM.
(1999-08-01)
Nearby terms:
Compact Disc interactive « Compact Disc Read-Only
Memory « Compact Disc Read-Write « Compact Disc
Recordable » Compact Disc Rewritable »
compaction » compactness preserving
Compact Disc Rewritable
<storage> (CD-RW) A rewritable version of CD-ROM. A CD-RW drive can write
about 650 megabytes of data to CD-RW media an unlimited number of times. Most
CD-RW drives can also write once to CD-R media.
CD-RW media cannot be read by CD-ROM drives built prior to 1997 due to the
reduced reflectivity (15% compared to 70%) of CD-RW media.
CD-RW drives and media are currently (1999) more expensive than CD-R drives and
media. CD-R is sometimes considered a better technology for archival purposes as
the data cannot be accidentally modified or tampered with, and encourages better
archival practices.
Standard prerecorded CDs have their information permanently stamped into an
aluminium reflecting layer. CD-WR discs have a phase-change recording layer and
an additional silver (aluminium) reflecting layer.
A laser beam can melt crystals in the recording layer into a non-crystalline
amorphous phase or anneal them slowly at a lower temperature back to the
crystalline state. The different reflectance of the areas make them appear as
the 'pits' and 'lands' of a standard CD.
Phillips: New Technologies.
See also CD-R and DVD-RAM.
(1999-08-01)
Nearby terms:
Compact Disc Read-Only Memory « Compact Disc
Read-Write « Compact Disc Recordable « Compact
Disc Rewritable » compaction » compactness
preserving » Compaq Computer Corporation
compaction
compression
Nearby terms:
Compact Disc Read-Write « Compact Disc Recordable «
Compact Disc Rewritable « compaction »
compactness preserving » Compaq Computer Corporation
» Compas Pascal
compactness preserving
In domain theory, a function f is compactness preserving if f c is compact
whenever c is.
(1995-01-13)
Nearby terms:
Compact Disc Recordable « Compact Disc Rewritable «
compaction « compactness preserving » Compaq
Computer Corporation » Compas Pascal » COMPASS
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