Relative Addressing (Ra) - ZiLOG Z8 PLUS User Manual

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RELATIVE ADDRESSING (RA)

In the Relative Addressing mode, illustrated in Figure 2-7, the instruction specifies a two's-complement
signed displacement in the range of –128 to +127. This is added to the contents of the Program Counter to
obtain the address of the next instruction to be executed. The PC (prior to the add) consists of the address of
the instruction following the Jump Relative (JR) or Decrement and Jump if Non-Zero (DJNZ) instruction. JR
and DJNZ are the only instructions which use this addressing mode.
JR or DJNZ
Program Memory
Next OpCode
Displacement
OpCode
Figure 2-7. Retrieve Addressing
Program Memory
Address Used
Current
PC Value