Push onto stack
The Stack Pointer is incremented by one. The contents of the indicated variable is then copied into the internal RAM location addressed by the Stack Pointer. Otherwise no flags are affected.
Encoding: 1 1 0 0 0 0 0 0 direct address
On entering an interrupt routine, the Stack Pointer contains 09H. The Data Pointer holds the value 0123H. The following instruction sequence,
PUSH DPL
PUSH DPH
leaves the Stack Pointer set to 0BH and stores 23H and 01H in internal RAM locations 0AH and 0BH, respectively.
Pop from stack
The contents of the internal RAM location addressed by the Stack Pointer is read, and the Stack Pointer is decremented by one. The value read is then transferred to the directly addressed byte indicated. No flags are affected.
Encoding: 1 1 0 1 0 0 0 0 direct address
The Stack Pointer originally contains the value 32H, and internal RAM locations 30H through 32H contain the values 20H, 23H, and 01H, respectively. The following instruction sequence,
POP DPH
POP DPL
leaves the Stack Pointer equal to the value 30H and sets the Data Pointer to 0123H. At this point, the following instruction,
POP SP
leaves the Stack Pointer set to 20H. In this special case, the Stack Pointer was decremented to 2FH before being loaded with the value popped (20H).
The Stack Pointer is incremented by one. The contents of the indicated variable is then copied into the internal RAM location addressed by the Stack Pointer. Otherwise no flags are affected.
Encoding: 1 1 0 0 0 0 0 0 direct address
On entering an interrupt routine, the Stack Pointer contains 09H. The Data Pointer holds the value 0123H. The following instruction sequence,
PUSH DPL
PUSH DPH
leaves the Stack Pointer set to 0BH and stores 23H and 01H in internal RAM locations 0AH and 0BH, respectively.
Pop from stack
The contents of the internal RAM location addressed by the Stack Pointer is read, and the Stack Pointer is decremented by one. The value read is then transferred to the directly addressed byte indicated. No flags are affected.
Encoding: 1 1 0 1 0 0 0 0 direct address
The Stack Pointer originally contains the value 32H, and internal RAM locations 30H through 32H contain the values 20H, 23H, and 01H, respectively. The following instruction sequence,
POP DPH
POP DPL
leaves the Stack Pointer equal to the value 30H and sets the Data Pointer to 0123H. At this point, the following instruction,
POP SP
leaves the Stack Pointer set to 20H. In this special case, the Stack Pointer was decremented to 2FH before being loaded with the value popped (20H).
Related topics:
8051 Complement Accumulator and Bit | 8051 Set Bit | 8051 Clear Accumulator and Bit | 8051 Rotate Accumulator | 8051 Swap Nibble | 8051 Exchange Accumulator | 8051 Exchange Digit | 8051 No Operation
List of topics: 8051
No comments:
Post a Comment