Just before the end of the year, I received an e-mail from my editorthat read, “We have a feature on network storage systems thatwe're trying to figger out, [so] what we'd like from you, your missionif you agree to accept it, is a glossary of common storage and networkterms. An IT glossary for the uninitiated pro audio folks. Whaddyathink? A whole column of pedants in a box.” So began this month's“Bitstream,” a bass-ackward version of my usual offering.[Note that italicized words are terms that will be defined in theglossary, some in upcoming parts.
Granted, I could never compete with the many excellent IT glossariesout there on the Web, but I've tried to gather the most commonTLAs, techie phrases and geek-speak for your edification. Forthose who need a bit of a mental housecleaning, this month will eithersweep away some cobwebs or increase your BBF by several ordersof magnitude!
1394: See IEEE 1394.
802.11: See IEEE 802.nx.
AAC (Advanced Audio Codec): an, um, advanced version of thewidely used MP3 perceptual sub-band/transform codec withadditional tools to reduce the encoded data rate while simultaneouslyreducing encoding artifacts. It is formally known as MPEG-2 AAC.
AAF (Advanced Authoring Format): an ad hoc standard promotedby a coalition of vendors, chiefly Avid and Microsoft, along withdevelopers and end-users. AAF is a wrapper file format.
Abstraction Layer: virtual programming buffers or softwareinsulators that reside between the inner details of some individualresource and any external entity that may want to use thatresource.
AC-3 (Audio Coded [Version] 3): Known to consumers as DolbyDigital, AC-3 is Dolby Laboratories' third generation of perceptualsub-band/transform codec. AC-3 is one of the mandated audio formatsfor both DVD-Video and ATSC Digital TV.
AIT (Advanced Intelligent Tape): a proprietary, mid-level,8mm, helical-scan data tape standard from Sony that pioneered thefeature of embedded memory in the cartridge.
AP (Access Point): An access point is a specially configurednode on a wireless network that bridges the WLAN and awired LAN.
API (Application Programming Interface): In the world ofsoftware, APIs are structured abstraction layers between thegory details of an individual application, operating system orhardware item and the world outside that software orhardware.
Application:executable software that provides usefultool(s) or function(s). In ye olden days, applications were called“programs.”
ASF (Active Streaming Format): a proprietary streamingformat developed by Microsoft that provides streaming media servicesfor the Windows Media framework.
ASP (Application Service Provider): a commercial entity thatsells Web services.
Asset: To a rich media geek, it's a file thatrepresents a valuable commodity or could be useful at some time in thefuture. Digital video or audio files are both considered assets.
Asymmetrical: refers to different, unequal or unbalanced dataservices, such as ADSL's send/receive data rate.
Asynchronous: refers, among other things, to techniques thatdo not require a common clock between communicating devices. BecauseIT streams and files are self-clocking, timing signals arederived from framing bits within the data stream.
ATM (Asynchronous Transfer Mode): a high-speed, fixed-packetdata transport standard that interoperates with the switched circuittelephony network. Although providing valuable QoSfeatures, ATM is being supplanted by less-expensive, IP-based standardsthat better interoperate with LANs and MANs.
Availability: as used by IT professionals, the amountof uptime. A product, system or service with three nines orbetter uptime is referred to as “high availability.”
Baseband: the lowest scale or simplest rate at whichmessaging occurs in a communications system.
Bit Rate: The data rate plus metadata and framingoverhead make up the bit rate. Data rate refers to the“raw” or baseband data rate over time at which somefile or stream is being delivered.
BBF (Bitstream Boggle Factor): the tendency for“Bitstream” readers' eyes to roll back into their heads asthe dense geek-speak causes the reader to fall into a deep sleep.
Bridge to Bridge: a device, either hardware or software, that“bridges” or connects two networks of the same type orprotocol.
Carrier Class: a marketing term used to denote a ruggedlyconstructed, full-featured product suitable for high-availability uses,as in, “This equipment is carrier class, buddy!”
CLEC (Competitive Local Exchange Carrier): the commercialentities created to compete with the ILECs when the Baby Bellswere broken up. Covad and OneEighty Networks are two examples ofCLECs.
Codec (Encoder/Decoder): a broad class of signal processingthat first transforms a signal from the original storage method intoanother to improve the distribution in some way. After distribution,the signal, or in our case data, is transformed back into somesemblance of the original. DTV, POTS and MP3 are all household examplesof codecs.
Coding, Coding Method: This refers to transforming orchanging the characteristics of a signal to make it more suitable forsome intended application, usually for transmission from one locationto another or for storage onto some medium that is different than theoriginal medium. Coding can improve fidelity, optimize carrierbandwidth, increase essence carriage, improve security orprovide error detection and correction.
COFDM (Coded Orthogonal Frequency Division Multiplexing): themodulation method chosen for U.S. domestic DAB service, someversions of ADSL and DTV services in Europe andAustralia. COFDM is used to encode or impose digital audio data onto ananalog carrier signal.
Co-Location: This refers to renting a designated space wherea company's servers are situated, along with other companies in thesame physical location. All machines share common HVAC and power. Forphysical security, each company usually has a lockable wire cage forits equipment.
DAB (Digital Audio Broadcast): the TLA for wireless digitalradio services, also known as IBOC/DAB. DAB is terrestrial radio inthat it's local or location-based, as opposed to national digitalsatellite “radio.” IBOC, or in-band on-channel, means thatDAB shoehorns a digital stream into the existing AM and FM analogservices, maintaining backward compatibility. DAB employs lossycodecs to reduce the transmitted data rate.
DAM (Digital Asset Management): a catch-all phrase thatdescribes the process of managing digital “assets,”files whose essence is deemed valuable by an organization. DAM usuallyrefers to audio, motion and still-image files in particular.
Data: Data is fundamentally any information of interest, butthese days, the word data implies a binary (base 2 arithmetic),machine-readable representation of information.
Data Center: a physical structure, usually a stand-alonebuilding, that is designed to house a multiplicity of computers. Datacenters can be private, serving a single company or, more commonly, apublic “utility” serving a variety of companies.
Data Rate: Often conflated with bit rate, data raterefers to the actual throughput or aggregate rate over time at whichthe essence is being delivered.
DDS (Digital Data Storage): DDS is a proprietary, entry-levelperformance, 8mm data tape standard originally based on the DAT, ordigital audio tape format. DDS is close to the end of the product lifecycle and is being supplanted by more modern formats such asVXA.
Directory Services: On a LAN or WAN, directoryservices provide an abstraction layer, identifying networkassets including users, resources and the various policiesassigned to each. The result is that resources and users are accessiblewithout possessing the details about a particular resource ornode. Directory services also abstract network topologiesand protocols.
Distributed: For an IT nerd, distributed meansdecentralized rather than concentrated in one node, physicallocation or server.
DLT (Digital Linear Tape): a proprietary, mid-level, lineardata tape standard originally developed by Matsushita.
To be continued next month…
OMas almost bit off more than he could chew when he took on thismonth's assignment. He couldn't have completed this installment withoutthe influence of Jean Luc Picard, er, Patrick Stewart's“engage”-ing spoken word recording of Charles Dickens'A Christmas Carol.