Sunday 25 December 2011

8085 µP instructions

Function of following 8085 µP instructions with examples (i) SHLD (ii) LDAX
       (i)    SHILD Address:
              Mnemonic : SHLD address
              Algorithm        :         (Address) ← L
                                      (Address + 1) ← H
              Operation       :         (Address) = L
                                      (Address + 1) = H
This instruction copies the contents of registers H and L to the memory location specified in instruction.
The contents of L register are stored at the memory location whose address is specified and the contents of register H to the next memory location.
              No. of bytes    :         3 bytes
              First Byte                 :         Opcode
              Second Byte   :         Low order byte of the address
              Third Byte      : High order byte of the address
              Addressing mode: Direct addressing mode
              Flags               :         No flags are affected.
              Example                   :         SHLD 5648 H.
              (ii)          LDAX Rp:
              Mnemonic                :         LDAX Rp
              Algorithm                 :         A ← (Rp)
              Operation                 :         A + (Rp)
This instruction copies the contents of memory location whose address is pointed by the specified register pair to the accumulator.
              The register Rp can be any valid register pair like BC or DE only.
              The contents of the memory location remain unchanged.
              No. of bytes    :         1 byte
                                                ode of LDAX Rp   
              ddressing mode        :        Register indirect addressing mode
              Flags               :         No flags are affected.

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