MC68HC05RC17 Datasheet, PDF (36/128 Pages) Freescale Semiconductor, Inc – General Release Specification

Freescale Semiconductor, Inc.
Central Processor Unit (CPU)
Negative (N)
When set, this bit indicates that the result of the last arithmetic, logical,
or data manipulation was negative.
Zero (Z)
When set, this bit indicates that the result of the last arithmetic, logical,
or data manipulation was zero.
Carry/Borrow (C)
When set, this bit indicates that a carry or borrow out of the arithmetic
logical unit (ALU) occurred during the last arithmetic operation. This bit
is also affected during bit test and branch instructions and during shifts
and rotates.
3.7 Stack Pointer
The stack pointer (SP) contains the address of the next free location on
the stack. During an MCU reset or the reset stack pointer (RSP)
instruction, the stack pointer is set to location $00FF. The stack pointer
is then decremented as data is pushed onto the stack and incremented
as data is pulled from the stack.
When accessing memory, the eight most significant bits are permanently
set to 00000011. These eight bits are appended to the six least
significant register bits to produce an address within the range of $00FF
to $00C0. Subroutines and interrupts may use up to 64 (decimal)
locations. If 64 locations are exceeded, the stack pointer wraps around
and loses the previously stored information. A subroutine call occupies
two locations on the stack; an interrupt uses five locations.
13
7
00000011
0
SP
General Release Specification
MC68HC05RC17 — Rev. 2.0
Central Processor Unit (CPU)
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