MC68HC05C8A Datasheet, PDF (38/158 Pages) Motorola, Inc – Microcontrollers

Central Processor Unit (CPU)
7
7
12
PC
12
7
0 0 0 0 0 11
A
0
0
X
0
0
SP
CCR
H INZC
ACCUMULATOR
INDEX REGISTER
PROGRAM COUNTER
STACK POINTER
CONDITION CODE REGISTER
Figure 3-1. Programming Model
7
0 _STACK
INCREASING
MEMORY
ADDRESSES
1 1 1 CONDITION CODE REGISTER _I
R
E
T
U
R
N
ACCUMULATOR
INDEX REGISTER
PCH
N
T
E
R
R
U
P
PCL
T
DECREASING
MEMORY
ADDRESSES
UNSTACK
NOTE: Since the stack pointer decrements during pushes, the PCL is stacked first,
followed by PCH, etc. Pulling from the stack is in the reverse order.
Figure 3-2. Stacking Order
3.3.1 Accumulator
The accumulator (A) shown in Figure 3-1 is a general-purpose 8-bit
register used to hold operands and results of arithmetic calculations or
data manipulations.
3.3.2 Index Register
The index register (X) is an 8-bit register used by the indexed addressing
value to create an effective address. The index register also may be
used as a temporary storage area.
Technical Data
38
MC68HC05C8A • MC68HCL05C8A • MC68HSC05C8A — Rev. 5.0
Central Processor Unit (CPU)
MOTOROLA