通用apdu指令

Introduction:

介绍：

In this article, we are going to discuss about the 6 general formats of instructions.

在本文中，我们将讨论6种通用指令格式。

1. One byte instruction:

   一字节指令 ：

   This is only one byte long and may have implied data and register.

   这只有一个字节长，可能包含隐含的数据和寄存器。

2. Register to register:

   注册注册 ：

   This instruction is 2 byte long. First byte specified opcode and width(w) of opcode and second byte specified register operand and R/M field.

   该指令为2个字节长。 第一个字节指定操作码和操作码的宽度(w)，第二个字节指定寄存器操作数和R / M字段。

   

   Here,

   这里，

   MSB - Most significant bit and LSB - Least significant bit

   MSB-最高有效位， LSB-最低有效位

3. Register to/from memory with no displacement:

   向内存中注册/从内存中迁移 ：

   This format is also 2-byte form and similar to the register except the MOD field.

   该格式也是2字节格式，除了MOD字段外，与寄存器相似。

4. Register to/from memory with displacement:

   通过位移向/从内存注册 ：

   This is same as the third one having one or two additional byte for displacement.

   这与第三位相同，具有一个或两个附加字节用于移位。

   

5. Immediate operand to register:

   立即操作数进行注册 ：

   In it first byte as well as three bits from the second byte which are used for the register field. In case of register to register format is reserved for the opcode. It also contains 1 or 2 bytes of immediate data.

   在它的第一个字节以及第二个字节之后的三个位用于寄存器字段。 如果是寄存器对寄存器格式，则保留操作码。 它还包含1或2个字节的立即数据。

   

6. Immediate Operand to memory with 16-bit displacement:

   立即操作数以16位位移到内存 ：

   

Opcode have single bit indicators their significance is as follows,

操作码具有单个位指示符，其含义如下：

• W bit: It tells us whether the instruction is to operate over an 8-bit or 16-bit

  W位 ：它告诉我们指令是在8位还是16位上运行

      W=0 /8bit
  W=1 /16bit
  
  

• D bit: It tells whether the register specified field is the source register or destination register.

  D位 ：告诉寄存器指定字段是源寄存器还是目标寄存器。

      D=0    Source register
  D=1    Destination
  
  

• S bit: This is called sign extension bit; it is used along with the w bit.

  S位 ：这称为符号扩展位； 它与w位一起使用。

      S   W
  0   0       8 bit operant with 8bit immediate
  0   1       operant. 16 bit operant with 6 bit
  0   1       immediate operant. 16 bit operation
  1   1       with sign extended immediate data.
  
  

• V bit: Used in case of shift and rotate instruction if v=0, then shift count is 1. If v=1 then count is stored into the CL register and count should be count=2.

  V位 ：如果v = 0，则在移位和旋转指令的情况下使用，则移位计数为1。如果v = 1，则将计数存储到CL寄存器中，并且计数应为count = 2。

• Z bit: This is used along with the string primitives such as REP for comparison with ZF flag.

  Z位 ：与Z标记的字符串原语(例如REP)一起使用。

Conclusion:

结论：

In the above article, I have discussed the different instruction formats of the microprocessors briefly, with relative diagrams also. As I said earlier at the beginning of this article also that this topic of computer system organization is very important from the examination point of view and also the base of your knowledge about computer architecture. For further queries shoot your questions in the comment section below!

在以上文章中，我简要讨论了微处理器的不同指令格式 ，并附带了相关图表。 就像我在本文开头所说的那样，从检查的角度以及计算机基础知识的基础来说，计算机系统组织这一主题非常重要。 如有其他疑问，请在下面的评论部分中提出您的问题！

翻译自: https://www.includehelp.com/embedded-system/general-instruction-formats-in-8086-microprocessor.aspx

通用apdu指令