Stack Operations Instructions (Part-II)

Stack Operations Instructions (Part-II) - SPHL and XTHL

SPHL:

This instruction copies the contents of HL register pair to the stack pointer (SP).
It means that the stack pointer will now point to the memory location whose address was given in the HL register pair.

No flags are affected.
It is a one byte instruction.
Register addressing mode is used.

Example:

If HL = 2030H, then

SPHL ; This instruction will copy 2030H into SP. So SP will point to the memory location 2030H.

XTHL:

This instruction exchanges the contents of the memory location pointed by stack pointer with the contents of the L register and the contents of the next memory location with the contents of H register.
This instruction does not alter the contents of the stack pointer.

No flags are affected.
It is a one byte instruction.
Register Indirect addressing mode is used.

Example:

If HL = 5601H, SP = 2000H, (2000H) = 30H and (2001H) = 20H, then

XTHL ; This instruction will exchange the contents of the memory location 2000H i.e. 30H with the contents of L register i.e. 01H and the contents of memory location 2001H i.e. 20H with the contents of H register i.e. 56H.

Before execution:

After execution:

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8085 Microprocessors Notes

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