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Important use of W and Z Registers

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W and Z Registers: 

  • These are temporary registers of 8085.
  • These registers are used to hold 8-bit data during execution of some instructions.
  • 8085 uses these registers internally.
  • These are not available for programmer.

Use of W and Z Registers:

CALL Instruction:
  • Whenever the processor wants to execute a subprogram or subroutine, CALL instruction is used to transfer program control to that subroutine. 
  • This instruction transfers the current PC contents onto the stack and loads the given address into PC. 
  • This address is temporarily stored in the W and Z registers.
XCHG Instruction:
  • This instruction exchanges the contents of H with D and L with E. 
  • At the time of exchange, W and Z registers are used as temporary registers.
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