計算機指令集_計算機科學組織| 指令集及其類型

計算機指令集

指令系統 (Instruction Set)

An

instruction set

can be defined as a group of instruction that a processor can execute to perform different operations. On the basis of complexity and the number of instruction used the instruction set can be classified as

指令集

可以定義為處理器可執行以執行不同操作的一組指令。 根據複雜性和使用的指令數量，可以将指令集分類為

1. Complex Instruction set

   複雜指令集

2. Reduced Instruction set

   精簡指令集

1)複雜指令集 (1) Complex Instruction set)

The complex instruction set is the set of instruction which includes very complex and large number of instructions. The number of instruction in this set varies from 100 to 250. The instruction in this set is mostly memory based instruction, which involves frequent to the memory. The complex instruction set makes use of a large number of addressing modes because of the frequent references to register as well as memory. The instruction in this instruction takes a lot of time because the instructions format which is not limited to only 32 bit.

複雜指令集是包括非常複雜和大量指令的指令集。 該集中的指令數量從100到250不等。該集中的指令主要是基于記憶體的指令，涉及到記憶體頻繁。 由于頻繁引用寄存器和存儲器，是以複雜的指令集使用了大量的尋址模式。 該指令中的指令要花費很多時間，因為指令格式不僅限于32位。

The complex which makes use of complex instruction set is called Complex Instruction set Computer (CISC). The instruction set of CISC has a large number of instruction and for each instruction type.

利用複雜指令集的複合體稱為複雜指令集計算機(CISC)。 對于每種指令類型，CISC的指令集都有大量指令。

Advantages of Complex Instruction Set 複雜指令集的優點

• There is no need to invent an instruction set for each new design. The instruction set of the predecessor is used by the new user.

  無需為每個新設計發明一套指令集。 新使用者使用前身的指令集。

• A program written in CISC require less memory space as the code is confined to less number of instruction.

  用CISC編寫的程式需要較少的存儲空間，因為代碼僅限于較少的指令數。

• CISC makes the job of a computer easier by facilitating the implementation of high-level language constructs.

  通過促進進階語言結構的實作，CISC使計算機的工作更加輕松。

Disadvantages of Complex Instruction set 複雜指令集的缺點

• The inheritance of old instruction into new processor increase the complexity.

  将舊指令繼承到新處理器中會增加複雜性。

• Many CISC instructions are not frequently used.

  許多CISC指令不經常使用。

• CISC command is translated into a large number of lines of microcode which makes the CPU processing slower.

  CISC指令被翻譯成大量的微代碼行，這使CPU處理速度變慢。

• CISC system has a complex hardware, so they require more times for designing.

  CISC系統具有複雜的硬體，是以需要更多的時間進行設計。

2)精簡指令集 (2) Reduced Instruction Set)

The reduced instruction set refers to a set of instruction that contains very few instructions ranging from 0 to 100. It comprises only those instruction that is frequently used by the processor for the execution of a program. The instruction is generally very simple to execute. The memory-based instruction includes the only load and stores instructions. The instruction in this instruction set has fixed length instruction format of 32 bits. An instruction format divides the bits of instructions into small group fields. Generally, an instruction has the following fields:

精簡指令集是指包含很少的0到100範圍内的指令的指令集。它僅包括處理器經常用于執行程式的那些指令。 該指令通常很容易執行。 基于存儲器的指令僅包括加載和存儲指令。 該指令集中的指令具有固定長度的32位指令格式。 指令格式将指令的位分成小組字段。 通常，一條指令具有以下字段：

• Opcode field 操作碼字段

  It represents the operations to be performed by the instruction.

  它代表指令要執行的操作。

• Operand field 操作數字段

  It represents the data on which the operations are to be performed or the memory location or registers where the data is stored.

  它表示要在其上執行操作的資料或存儲該資料的存儲器位置或寄存器。

• Mode field 模式字段

  It represents the method of fetching the operands stored at specified memory location or register.

  它表示擷取存儲在指定存儲位置或寄存器中的操作數的方法。

The comparison of RISC and CISC processor indicated that the RISC processor is always preferred over the CISC processor because of their compact size and small instruction set.

RISC和CISC處理器的比較表明，RISC處理器始終比CISC處理器更受青睐，因為它們具有緊湊的尺寸和小的指令集。

Advantages of Reduced Instruction set computer 精簡指令集計算機的優勢

The other advantages of RISC processor over the CISC processor are as follow:

RISC處理器相對于CISC處理器的其他優點如下：

• In RISC processor the instructions are executed by decoding but in CISC processors, the instructions are executed by first and then translating them into equivalent microcode instructions. The conversion of instruction into microcode consumes a lot of space in the memory thereby reducing the speed of executions.

  在RISC處理器中，指令是通過解碼執行的，而在CISC處理器中，指令是先執行的，然後将其轉換為等效的微碼指令。 将指令轉換為微代碼會占用記憶體中的大量空間，進而降低了執行速度。

• The RISC processor executes an instruction in a single clock cycle, while the CISC processor requires multiple clocks cycles for the execution of an instruction.

  RISC處理器在單個時鐘周期内執行一條指令，而CISC處理器則需要多個時鐘周期才能執行一條指令。

Disadvantages of Reduced Instruction set computer 精簡指令集計算機的缺點

The only disadvantages of RISC in comparison to CISC is that the number of instructions required to perform an operation is comparatively large.

與CISC相比，RISC的唯一缺點是執行操作所需的指令數量相對較大。

翻譯自: https://www.includehelp.com/cso/instruction-set-and-their-types.aspx

計算機指令集