XC912BC32CFU8 Motorola Semiconductor Products, XC912BC32CFU8 Datasheet - Page 63

• Manufacturer Part Number: XC912BC32CFU8
• Description: M68HC12B Family Data Sheet
• Manufacturer: Motorola Semiconductor Products

3.3.3 Index Registers X and Y
M68HC12B Family — Rev. 8.0
MOTOROLA
Reset:
Reset:
Read:
Read:
Write:
Write:
Bit 15
Bit 15
X15
Y15
NOTE:
NOTE:
X14
Y14
14
14
X13
Y13
13
13
Index registers X and Y are used for indexed addressing. Indexed addressing adds
the value in an index register to a constant or to the value in an accumulator to form
the effective address of the operand.
Index registers X and Y can also serve as temporary data storage locations.
The LDX and STX instructions can be used to manipulate data in and out of index
register X.
The LDY and STY instructions can be used to manipulate data in and out of index
register Y.
X12
Y12
12
12
X11
Y11
11
11
Figure 3-5. Index Register X (X)
Figure 3-6. Index Register Y (Y)
X10
Y10
10
10
Central Processor Unit (CPU)
X9
Y9
9
9
Unaffected by reset
Unaffected by reset
X8
Y8
8
8
X7
Y7
7
7
X6
Y6
6
6
X5
Y5
5
5
X4
Y4
4
4
Central Processor Unit (CPU)
X3
Y3
3
3
X2
Y2
2
2
CPU Registers
X1
Y1
1
1
Data Sheet
Bit 0
Bit 0
X0
Y0
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