| 单词 | frame |
| 释义 | frame 1. A structure in the form of a structure of metal uprights and cross pieces with termination points on each side into which components can be mounted and conductors can be mechanically connected. The term is applied to distribution frames for cables and is the origin of the term mainframe computer. 2. In asynchronous serial data communications, a transmission unit comprising a character of data and one or two parity bits, preceded by a start bit, succeeded by a stop bit. Asynchronous communications are said to be character-framed. See Figure F-5. See also asynchronous transmission. 3. In synchronous data communications protocols such as HDLC and SDLC, a message unit. A frame comprises control data, address data, user data, and an error control mechanism.The frame is preceded by a beginning flag and succeeded by an ending flag. The data field of an SDLC frame, for example, can comprise as many as 4,096 octets and the various control fields add another four or six octets. See Figure F-6. See also SDLC and synchronous transmission. 4. In digital carrier systems E-carrier, J-carrier, and T-carrier, a collection of time slots that repeats every 125 microseconds. In a channelized application, each time slot constitutes a channel. In an unchannelized application, the entire collection of time slots constitutes a channel. Figure F-7 is an illustration of a channelized T1 frame. Note: A T1 and J1 frame is always preceded by a framing bit, which is used for synchronization and other control purposes. An E-1 frame does not require a framing bit, as time slots 0 and 16 serve those functions. See also carrier, channel, E-carrier, framing bit, J-carrier, synchronous, T-carrier, and time slot. 5. In video communications, a single photographic image that is one of many in a motion picture. See also frame rate. Start Parity Stop 1 2 3 4 5 6 7 Bit Bit Bit |
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