MC68HC05P18 Datasheet, PDF (38/144 Pages) Freescale Semiconductor, Inc – Advance Information

Freescale Semiconductor, Inc.
Central Processing Unit (CPU)
3.3.3.3 Negative (N)
When set, this bit indicates that the result of the last arithmetic, logical,
or data manipulation was negative.
3.3.3.4 Zero (Z)
When set, this bit indicates that the result of the last arithmetic, logical,
or data manipulation was 0.
3.3.3.5 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.
3.3.4 Stack Pointer (SP)
The stack pointer 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 seven most significant bits are
permanently set to 0000011. These seven 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.
12
7
00 00011
0
SP
Advance Information
38
MC68HC(8)05P18 — Rev. 2.0
Central Processing Unit (CPU)
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