计算机内存单元大小_计算机科学组织| 控制单元-蒲公英云

计算机内存单元大小

硬线控制单元 (Hardwired Control Unit)

Hardware control unit can be viewed as a state machine which will change from one state to another in every clock cycle depending on the content of the instruction register, external inputs and the codes used in it.

硬件控制单元可以看作是一种状态机，它将在每个时钟周期内从一种状态变为另一种状态，具体取决于指令寄存器的内容，外部输入和其中使用的代码。

The hardwired control unit is implemented as a sequential logic circuit or a finite state machine which will generate a specific sequence of the control signal to execute an instruction. The hardwired control unit uses the logic to interpret the instruction and generate control signals. While designing such type of control unit various factors are considered which are:

硬接线控制单元被实现为顺序逻辑电路或有限状态机，它们将生成控制信号的特定序列以执行指令。硬连线控制单元使用逻辑来解释指令并生成控制信号。在设计这种类型的控制单元时，需要考虑以下因素：

Cost of designing

设计成本
Number of hardware used

使用的硬件数量
Speed of the operation (performance)

操作速度(性能)

Control Unit | CSO

Generally, there are four techniques for designing a Hardwired control unit they are as follows:

通常，设计硬接线控制单元有以下四种技术：

State table method: It is a simple method of sequential circuit design. Its attempt is to minimize the amount of hardware.

状态表方法：这是时序电路设计的一种简单方法。其尝试是最大程度地减少硬件数量。
Delay element method: It is a method which is based on the use of D flip-flop for control signal timing.

延迟元件法：这是一种基于D触发器控制信号时序的方法。
Sequence counter method: It uses the counter for the timing purposes.

序列计数器方法：它使用计数器进行计时。
PLA method: It uses the programmable logic array.

PLA方法：它使用可编程逻辑阵列。

Advantages of Hardwired Control unit:

有线控制单元的优点：

It is faster than the microprogrammed control unit.

它比微程序控制单元快。
It can be optimized to produce the fast mode of operation.

可以对其进行优化以产生快速的操作模式。

Disadvantages of Hardwired control unit:

有线控制单元的缺点：

Instruction set, the control logic is directly implemented.

指令集，控制逻辑直接实现。
Requires change in wiring if the design has to be controlled.

如果必须控制设计，则需要更改接线。
An occurrence of an error is more.

错误的发生更多。
Complex decoding and sequencing logic.

复杂的解码和排序逻辑。
It requires a more chip area, therefore, it is a costlier control unit.

它需要更大的芯片面积，因此，它是一个成本更高的控制单元。

微程序控制单元 (Micro-Programmed Control Unit)

In the microprogrammed control unit, microinstructions are stored in a memory called control memory. In a response to a machine instruction, a set of a microinstruction is executed by which each microinstruction will generate a set of the control signals i.e. execution of a set of microinstructions will resemble the execution of a program.

在微程序控制单元中，微指令存储在称为控制存储器的存储器中。响应于机器指令，执行一组微指令，每个微指令将通过该微指令生成一组控制信号，即，执行一组微指令将类似于程序的执行。

A micro instruction consists of:

一条微指令包括：

One or more microinstruction to be executed

一个或多个要执行的微指令
Address of the next microinstruction to be executed

下一条要执行的微指令的地址

A microinstruction can cause the execution of one or more micro-operation and sequence of the microinstruction can cause execution of the instruction. The microprogram consists of the microinstruction which is generally nothing but a string of 0 and 1. In this if the content of the memory cell is 0, it will indicate, that the signal is not generated and is the content of the memory cell is 1 then it will indicate to generate the control signal at a time.

一条微指令可能导致一个或多个微操作的执行，并且该微指令的顺序可能导致指令的执行。微程序由微指令组成，该微指令通常只不过是0和1的字符串。在这种情况下，如果存储单元的内容为0，则将指示未生成信号，并且该存储单元的内容为1。那么它将指示一次生成控制信号。

Microprogram in CSO

On execution of microinstructions at memory address 0000, C1, C2, C5, C7, C8 will be generated. Address of the next instruction is provided by the address field.

在存储器地址0000处执行微指令时，将生成C1，C2，C5，C7，C8。下一条指令的地址由地址字段提供。

Functioning of micro programmed control unit:

微型程序控制单元的功能：

The control unit can generate the control signal for any instruction by sequentially reading the control word of the corresponding microprogram from the memory.

控制单元可以通过从存储器中顺序读取相应微程序的控制字来生成任何指令的控制信号。
To read the control word sequentially from the microprogram memory, a microprogram counter is needed.

为了从微程序存储器顺序读取控制字，需要一个微程序计数器。
The starting address block is responsible for the loading. The starting address of the microprogram into the PC provides a new instruction which is loaded into IR.

起始地址块负责加载。微程序到PC的起始地址提供了一条新指令，该指令已加载到IR中。
The PC is then automatically incremented by the clock, and it reads the successive microinstruction from the memory.

然后，PC自动按时钟递增，并从存储器读取连续的微指令。
By this, each microinstruction provides the control signal and the microprogram counters ensure that the control signal will be delivered to the various parts of the CPU in the correct sequence.

这样，每个微指令都提供控制信号，并且微程序计数器确保控制信号将以正确的顺序传送到CPU的各个部分。

Advantages of Micro Programmed Control unit:

微程序控制单元的优点：

It is both cheaper and the occurrence of an error is less.

它既便宜，又减少了错误的发生。
More flexible to accommodate with new instructions.

更灵活地适应新指令。
Easier decoding and sequencing can be done.

可以更轻松地进行解码和排序。
Easier to handle complex instruction sets.

更容易处理复杂的指令集。
It requires a less chip area.

它需要较小的芯片面积。

Disadvantages of Micro programmed control unit:

微程序控制单元的缺点：

This is slower than the hardwired control unit because the microinstructions are to be fetched from the control memory which is time-consuming.

这比硬连线的控制单元要慢，因为要从控制存储器中提取微指令，这很耗时。

需要控制单元 (Need of control unit)

The control unit is very essential as a state machine circuit in which input signal is transformed into a set of output logic signals which are termed as control signals. As the control unit manages the translation of instruction and the scheduling of the microinstruction between the execution units.

控制单元作为状态机电路非常重要，在该状态机电路中，输入信号被转换为一组输出逻辑信号，这些逻辑信号被称为控制信号。由于控制单元管理执行单元之间的指令翻译和微指令的调度。

References:

参考文献：

https://www.geeksforgeeks.org/computer-organization-hardwired-vs-micro-programmed-control-unit/

https://www.geeksforgeeks.org/computer-organization-hardwired-vs-micro-programmed-control-unit/
https://www.sanfoundry.com/computer-organization-problems/

https://www.sanfoundry.com/computer-organization-problems/