SDDS (Sony Dynamic Digital Sound): Sony’s 12-channel professional version of its ATRAC lossy codec used for motion picture soundtracks.
SDK (Software Developer Kit, Software Development Kit): a collection of programming “interfaces” or abstractions, shortcuts, reusable subroutines or “libraries,” and documentation that allows a third party to create software accessories for an existing software product or family.
SDLT (Super D): See DLT.
SDMI (Secure Digital Music Initiative): Yet another clueless attempt by the RIAA to “protect” digital assets.
Sector: the minimum track length or logical assignment that can be used to store information on a magnetic disk or optical disc.
Serial: The opposite of parallel, a serial approach to data handling uses a single path rather than the multiple paths employed by the parallel approach.
Server: In Ye Olden Days, computers were big and expensive — very expensive. During that era, the “client/server” model was born, whereby all of the investment in hardware, software, infrastructure and personnel was centralized in one big computer: the server. In modern computing environments, it is still often sensible to centralize some computing resources, such as backup, with servers.
SFTP (Secure File-Transfer Protocol): Secure FTP provides basic, secure file and directory management between remote computer systems.
SGML: See xML.
Simplex: A simplex connection provides simultaneous bi-directional data transfer, in which each channel continuously transmits in both directions.
SMB (Server Message Block, Small Medium Business): The Server Message Block protocol, invented by Microsoft, is used to share Windows file systems over a network. The Small Medium Business version is a favorite of IT vendors, considering that sales to large-scale businesses are increasingly flat. See CIFS.
SMIL (Synchronized Multimedia Integration Language): The W3C defines SMIL as, “The Synchronized Multimedia Integration Language enables simple authoring of interactive audio/visual presentations.”
SOAP (Simple Object Access Protocol): SOAP is a lightweight, stateless, one-way messaging protocol for the exchange of information in a distributed environment. SOAP is often used in Web Services.
Software: Known in Ye Olden Days as “programs,” software is a collection of instructions that cause a computer to perform some useful function.
SONET (Synchronous Optical NETwork): a Layer 1, physical high-bandwidth telephony transport protocol that provides interoperability between disparate carriers’ optical infrastructure.
Spyware: See malware.
Stateful: A stateful paradigm refers to maintaining a well-defined state, as opposed to stateless or impromptu operation. Stateful operation can be applied to an application running in a memory partition on a computer or a telephone call with its switched-circuit connection. In a phone call, a temporary circuit is built and the two or more parties are patched in. That temporary circuit or “state” is then broken down after the phone call is terminated.
Stateless: Also known as connectionless, a stateless paradigm refers to moment-by-moment operation. Ethernet is an example of a stateless, packet-switched protocol, in which there is no fixed connection between end nodes.
Storage: In the world of IT, storage refers to any device or subsystem that holds some data for future use. Storage is usually implied to be nonvolatile and can employ magnetic, physical, optical or quantum techniques to store the information.
Store and Forward: In a store-and-forward approach to data transfer, a download is initiated and the desired data is stored and then operated on locally. This is the opposite of streaming.
STP (Shielded Twisted Pair): In IT land, shield cable is more rare than unshielded varieties and is only used for very high-speed Bs or in “hostile” environments, in which high levels of RFI and EMI are present.
Stream, streaming: A stream of data refers to a real-time flow and use of data from a source, usually a Web server, to a sink or destination, usually a Web client or browser. This differs from the store-and-forward method in that a stream is not usually, or casually, saved to the local client. Streaming can be thought of as transitory data transfer, which is by design, because streaming is used by content providers to lessen a consumer’s ability to redistribute the streamed content. As with all attempts to selectively prohibit unauthorized use and reuse of digital content, modern software allows streams to be captured locally for later reuse.
Subnet: a logical subdivision of a LAN used to partition network activity and resources.
Switch, to switch: A switch connects multiple nodes together in a direct, virtual point-to-point method rather than a broadcast method. A switch specializes in exchanging packets within a subnet. In the TCP/IP world of Ethernet, a switch is typically a Layer 2 or data link layer device that provides filtering and forwarding of packets. Layer 3 switches are also manufactured, providing routing via hardware at “wire speeds.” Switches can either be “managed,” meaning that they have remote control over operating parameters, or “unmanaged,” which means all parameters are factory-preset. Unmanaged switches are also known as “dumb” switches.
Switch(ed)-fabric: A switch-fabric architecture decouples I/O operations from memory by using channel-based point-to-point connections rather than the shared bus, load and store configuration of older technologies.
Subnet: a set of nodes that are interconnected and “agree” on a common set of device addresses. In the TCP/IP world, subnets encompass all devices whose IP addresses have the same prefix.
Symbol: In IT speak, a symbol is the logical equivalent of some physical variable that encodes a datum.
Synchronous: The opposite of asynchronous, synchronous means either that two or more data paths require a common timing signal or that two or more signals are operating at the same symbol rate or employ identical symbol sequences.
T-n: Used to designate various tiers of leased telco services, T1 or T-1 represents a stateful connection or circuit that provides 1.544 Mbps of symmetrical bandwidth between end points. T-1, quite costly relative to newer packet-based WAN services, is also available in “fractional” increments of 128 kbps, which reduces the monthly cost in trade for less bandwidth.
Target: can be thought of as a device, such as a disk array or network adapter, that receives command from another node, device, application or service.
TB, terabyte: A terabyte, though not precisely so, is commonly thought of as 1,000 Megabytes.
TCA (Target Channel Adapter): the IB component that connects an input/output device to other IB devices. TBAs only require support for capabilities appropriate to the particular input/output device. TCAs are used inside of, or are attached to, a device, such as a solid-state memory cache, or device group, such as a tape library.
Welly well, my droogs, we’re almost done with this darn Pedants thing, so this new year, I’ll continue to split time between emerging trends and plain ol’ useful geek intelligence
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