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CMP

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  Syntax: CMP R Where R can be any of the general purpose registers (A,B,C,D,E,H and L) Byte: 1byte Addressing Mode: Register   Addressing Working:  1. This is one byte instruction. 2. microprocessor will allocate one byte for opcode CMP and operands are registers i.e. operands don't need memory allocations for execution here. 3. T his instruction compares the content of the register R with content of the Accumulator. The comparison is done using subtraction of the content of register from the Accumulator .  The content of Accumulator remains unchanged . Conditions of Comarison:   1.  If [A] < [R] then Cy flag is set i.e. Cy =1 . 2. If [A] = [R]  then Z flag is set i.e Z=1. 3. If [A] > [R]  then Cy and Z flags are reset. i.e Cy = 0 and  Z = 0 4. Flag Example: CMP B where  [B] = 22H  and [A]= 11H After execution of CMP B [A] = 11H [B] = 22H   2's complement subtraction: A= 11 =  0001 0001 B= 22 =  0010 0010 1'...
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Microprocessor 8085 Instructions

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Instructions of 8085 can be classified on three basis:  First Classification on basis of their byte length i.e. size of instruction. 1.  1-byte instructions 2. 2-byte instructions 3.  3-byte instructions Second Classification on basis of their addressing modes i.e. kinds of approaches to fetch and execute. 1. Register Addressing 2. Immediate Addressing 3. Direct Addressing 4. Register Indirect Addressing 5. Implicit Addressing There are five sets of instructions for 8085mp  Programming:  1. Data Transfer group 2. Arithmetic group 3. Logical group 4. Branching group 5. Machine Control group
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RRC

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  Syntax: RRC   Byte: 1byte   Addressing Mode: Implicit Addressing Working:  1. This is one byte instruction. 2. Microproccessor will allocate one byte for opcode RRC and operand is Accumulator i.e. operand will not need memory allocation during execution. 3. Thi s instruction rotates content of Accumulator one bit position towards Right.   i.e. The bit A0 is stored  in carry flag AS WELL AS  will get stored in A7 bit position.   4. C Flag will get affected. Example: RRC   where   [A]= 21H After execution of RRC [A] = 90H     A= 21 =  0010 0001 A7 ->  A6 -> A5 -> A4 -> A3 -> A2 -> A1 -> A0   -> Cy    |___<-____________________________<-_ __| 0         0         1        0       0        ...
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