【免费下载】计算机专业英语教案第2章

计算机专业英语第2章Hardware Knowledge 1 第2章Hardware Knowledge2.1 Computer Hardware Basics2.2 CPU2.3 Memory2.4 Input / Output Devices2.5 Parallel Organization2.1 Computer Hardware Basics•Flip-Flop and Clock•Shift registers•Combinational Circuit•Logic Systems•Logic CircuitsFlip-Flop and Clock•Microprocessors employ both latches and flip-flops.• A flip-flop is a synchronous device; it is clocked, and it can change state only on arrival of a clock pulse.•Clock pulses are basically square waves; they may have a very low repetition, or they may have a very high repetition rate.计算机专业英语第2章Hardware Knowledge 2 RS flip-flopShift registers• A register capable of shifting its binary information in one or both directions is called a shift register.•All flip-flops receive common clock pulses that initiate the shift from one stage to the next.• A register capable of shifting in one direction only is called a unidirectional shift register. A register that can shift in bothdirections is called a bi-directional shift register.•Some shift registers provide the necessary input terminals for parallel transfer.4-bit shift registerThe capabilities of register•An input for clock pulses to synchronize all operations.• A shift-right operation and a serial input line associated with theshift-right.• A shift-left operation and a serial input line associated with the shift-left.• A parallel load operation and n input lines associated with the parallel transfer.•N parallel output lines.• A control state that leaves the information in the register unchanged even though clock pulses are applied continuously. Combinational Circuit• A combinational circuit is a connected arrangement of logic gates with a set of inputs and outputs. At any given time, the binary values of the outputs are a function of the binary combination of the inputs.• A combinational circuit can be described by a truth table showing the binary relationship between the n input variables and the m output variables.Block diagram of a combinational circuitLogic Systems•In a DC, or level-logic, system a bit is implemented as one of two voltage levels. If the more positive voltage is the 1 level and the other is the 0 level, the system is said to employ DC positive logic.•The digital levels are not specified precisely, but each state is defined by a voltage range about a designated level, such as 4V±1V and 0.2V±0.2V.•In a dynamic, or pulse-logic, system a bit is recognized by the presence or absence of a pulse.Logic Circuits•The design of digital computers is based on a logical methodology called Boolean Algebra which uses three basic operations: logical addition, called the OR function; logical multiplication, called the AND function; and logical complementation, called the NOT function.•The variables in Boolean algebra are binary, namely, the resulting variable of an operation or a set of operations can have only one of the two values: One or Zero.Key Words•arbitrary 任意的•arrangement 排列，整理•asynchronous 异步的•bi-directional 双向的•Boolean function 布尔函数•cascade 级连的，串级•combinational circuit 组合电路•complement 补充，补足•configuration 配置，结构•flip-flop 触发器•inasmuch 因……之故•inhibit 禁止，抑制•initiate 开始，激发•interconnection 互联网络•microprocessor 微处理器•negative-logic 负逻辑•parallel transfer 并行传送•serial 顺序的，串行的•significance 重要性，意义•square-wave 方波•unidirectional 单向的Notes•[1] The logical configuration of a shift register consists of a chain of flip-flops in cascade, with the output of one flip-flop connectedto the input of the next flip-flop.•此句中的“with the output of one flip-flop connected to the input of the next flip-flop”是独立结构作状语，说明触发器连接的方式。

•译文：移位寄存器的逻辑结构是由一连串串接的触发器所组成的，一个触发器的输出端连接到相邻的触发器的输入端。

•[2] Sometimes it is necessary to control the shift so that it occurs with certain clock pulses but not with others.•此句中的“it”是形式主语，“to control the shift”是真正主语，so that引导状语从句。

•译文：有时候有必要对移位进行控制以便移位只对某些特定脉冲而不对其他脉冲发生。

•[3] A register that can shift in both directions is called a bi-directional shift register.•本句用被动语态表示客观性，“that can shift in both directions”是主语从句，修饰“a register”。

•译文：能够在两个方向上移位的寄存器叫做双向移位寄存器。

•[4] A combinational circuit transforms binary information from the given input data to the required output data.•本句的介词短语“from … to …”作宾语补足语，进一步说明宾语“binary information”。

•译文：组合电路通过传输二进制信息，使得给定的输入数据产生了所需要的输出数据。

•[5] A combinational circuit can also be specified with m Boolean functions, one for each output variable.•本句的“one for each output variable”是同位语。