DCR
Syntax: DCR R
Where R can be any of the general purpose registers (A,B,C,D,E,H andL)
Byte: 1byte
Addressing Mode: Register Addressing
Working:
1.
2.
3.
4. Flag
Example: DCR B
Where [B]= 10H
After execution of DCR B
[B]= 0F H
XRI
Syntax: XRI 8-bit Where 8- bit is an immediate operand data. Byte: 2byte Addressing Mode: Immediate Addressing Working: 1.This is 2 byte instruction. 2. Microprocessor will allocate first byte for opcode and second byte for immediate data. 3. During execution of this instruction, microprocessor will perform Logical XORing operation between content of Accumulator and Immediate data. 4. S, Z and P are modified . Cy and Ac are reset . Example: XRI 22H where [A]= 11H After execution of XRI 22H [A] = 33H A= 11 = 0001 0001 = 22 = 0010 0010 A=33= 0011 0011 FLAG= 00 0 0 0 1 0 0 = 04H
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