MC68HC705C4ACB MOTOROLA [Motorola, Inc], MC68HC705C4ACB Datasheet - Page 46

• Manufacturer Part Number: MC68HC705C4ACB
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

Central Processor Unit (CPU)
3.3.3 Stack Pointer
Technical Data
46
Reset:
Read:
Write:
Bit 12
0
0
The stack pointer (SP) shown in
contains the address of the next free location on the stack. During a reset
or after the reset stack pointer (RSP) instruction, the stack pointer
initializes to $00FF. The address in the stack pointer decrements as data
is pushed onto the stack and increments as data is pulled from the stack.
The seven most significant bits of the stack pointer are fixed
permanently at 0000011, so the stack pointer produces addresses from
$00C0 to $00FF. If subroutines and interrupts use more than 64 stack
locations, the stack pointer wraps around to address $00FF and begins
writing over the previously stored data. A subroutine uses two stack
locations. An interrupt uses five locations.
= Unimplemented
11
0
0
10
0
0
Central Processor Unit (CPU)
9
0
0
Figure 3-4. Stack Pointer (SP)
8
0
0
7
1
1
MC68HC705C4A • MC68HSC705C4A — Rev. 3.0
Figure 3-4
6
1
1
5
1
is a 13-bit register that
4
1
3
1
2
1
MOTOROLA
1
1
Bit 0
1