字电子技术,英文版,chapter01.ppt

* Alt+十进制数＝ * 非理想状态下的脉冲：脉宽、幅度、上升时间、下降时间等 * 占空比 * 位时间或位间隔 * 数字系统中，所有的波形都与一个基本时序波形同步（时钟）， * * The Encoding Function（编码） The encoding function is performed by a logic circuit called an encoder. The encoder converts (noncoded) information (for example, a calculator keystroke) into some binary code. * The Decoding Function（解码） The decoding function is performed by a logic circuit called an decoder. The decoder converts a binary code into some (noncoded) information (for example, a decimal digit). * The Multiplexing Function（多路转换） The multiplexing function is performed by a logic circuit called a multiplexer, or mux for short. The mux switches digital data from several input lines onto a single output line in a specified time sequence. * The Demultiplexing Function（多路复用） The demultiplexing function is performed by a logic circuit called a demultiplexer, or demux for short. The demux switches digital data from one input line to several output lines in a specified time sequence. * Time Division Multiplexing (TDM)（时分复用） Multiplexing and demultiplexing are used when data from several sources are to be transmitted over one line to a distant location and redistributed to several destinations. * A KVM Switch This KVM switch allows four computers to share a single keyboard, video monitor, and mouse. * The Storage Function（存储） When an input is applied to a circuit, the output will change its state, but it will remain in the new state even after the input is removed. This property of retaining its response to a momentary input is called memory. The purpose of storage is to retain binary data for a period of time. Common types of storage devices are flip-flops, registers, semiconductor memories, magnetic disks, magnetic tape, and optical disks. * Flip-flops（触发器） The flip-flop is a bistable (two stable states) logic circuit that can store only one bit at a time, either a 1 or a 0. The output of a flip-flop indicates which bit it is storing. * Flip-flops * Registers（寄存器） A re