第2章Hardware Knowledge
2.1 Computer Hardware Basics
2.2 CPU
四级成绩查询时间2.3 Memory
2.4 Input / Output Devices
2.5 Parallel Organization
2.1 Computer Hardware Basics
•Flip-Flop and Clock
•Shift registers
•Combinational Circuit
•Logic Systems
menuitem•Logic Circuits
Flip-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 pul.
•Clock puls are basically square waves; they may have a very low repetition, or they may have a very high repetition rate.
RS flip-flop
Shift 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 puls 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 both directions is called a bi-directional shift register.
•Some shift registers provide the necessary input terminals for parallel transfer.
4-bit shift register
The capabilities of register
•An input for clock puls to synchronize all operations.美国之声第七季
• A shift-right operation and a rial input line associated with the大懒猫英语
shift-right.
• A shift-left operation and a rial input line associated with the shift-left.
• A parallel load operation and n input lines associated with the parallel transfer.
ekaterina makarova•N parallel output lines.
• A control state that leaves the information in the register unchanged even though clock puls are applied continuously. Combinational Circuit
• A combinational circuit is a connected arrangement of logic gates with a t of inputs and outputs. At any given time, the binary values of the outputs are a function of the binary combination of the inputs.
well done是什么意思中文• 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 circuit
Logic 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 precily, 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 pul-logic, system a bit is recognized by the prence or abnce of a pul.
Logic Circuits
•The design of digital computers is bad on a logical methodology called Boolean Algebra which us 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 t 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 组合电路满足的英文
•complement 补充，补足
•configuration 配置，结构
•flip-flop 触发器
•inasmuch 因……之故
•inhibit 禁止，抑制jojoba
•initiate 开始，激发
•interconnection 互联网络
•microprocessor 微处理器
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•negative-logic 负逻辑
•parallel transfer 并行传送
•rial 顺序的，串行的
•significance 重要性，意义
•square-wave 方波
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•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 connected
