MC9S12T64 Datasheet, PDF (28/608 Pages) Motorola, Inc – Specification

Freescale Semiconductor, Inc.
Central Processing Unit (CPU)
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Read:
Write:
Reset: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Figure 5 Index Register X
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Read:
Write:
Reset: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Figure 6 Index Register Y
Stack Pointer (SP)
The stack stores system context during subroutine calls and interrupts,
and can also be used for temporary data storage. It can be located
anywhere in the standard 64K byte address space and can grow to any
size up to the total amount of memory available in the system.
SP holds the 16-bit address of the last stack location used. Normally, SP
is initialized by one of the first instructions in an application program. The
stack grows downward from the address pointed to by SP. Each time a
byte is pushed onto the stack, the stack pointer is automatically
decremented, and each time a byte is pulled from the stack, the stack
pointer is automatically incremented.
When a subroutine is called, the address of the instruction following the
calling instruction is automatically calculated and pushed onto the stack.
Normally, a return from subroutine (RTS) is executed at the end of a
subroutine. The return instruction loads the program counter with the
previously stacked return address and execution continues at that
address.
MC9S12T64Revision 1.1.1
Central Processing Unit (CPU)
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