Short for High-level Data Link Control, a transmission protocol used at the data link layer (layer 2) of the OSI seven layer model for data communications. The HDLC protocol embeds information in a data frame that allows devices to control data flow and correct errors. HDLC is an ISO standard developed from the Synchronous Data Link Control (SDLC)standard proposed by IBM in the 1970’s.
For any HDLC communications session, one station is designated primary and the other secondary. A session can use one of the following connection modes, which determine how the primary and secondary stations interact.
Normal unbalanced: The secondary station responds only to the primary station.
Asynchronous: The secondary station can initiate a message.
Asynchronous balanced: Both stations send and receive over its part of a duplex line. This mode is used for X.25 packet-switching networks.
The Link Access Procedure-Balanced (LAP-B) and Link Access Procedure D-channel (LAP-D)protocols are subsets of HDLC.
Handheld Device Markup Language is used to format content for Web-enabled mobile phones. HDML is Openwave’s (formerly known as phone.com) proprietary language, which can only be viewed on mobile phones that use Openwave browsers. HDML came before the WAP standard was created. It uses Openwave’s Handheld Device Transport Protocol (HDTP), instead of WAP. Phones access […]
Short for hard disk recorder, another name for a personal video recorder.
Short for High-Definition Television, a new type of television that provides much better resolution than current televisions based on the NTSC standard. HDTV is a digital TV broadcasting format where the broadcast transmits widescreen pictures with more detail and quality than found in a standard analog television, or other digital television formats. HDTV is a […]
HDTV-ready refers to a television set which does not come with an integrated HDTV tuner. You must purchase the tuner (also called the HDTV receiver, set-top box, or HDTV decoder) separately.
- HDTV tuner
A device capable of receiving and outputting HDTV signals for display. HDTV tuners can be a stand-alone device or it can integrated in the HDTV display. HDTV has many different consumer names including HDTV decoder, HDTV receiver, and set-top box.