XC908AS60ACFU Motorola Semiconductor Products, XC908AS60ACFU Datasheet - Page 131

• Manufacturer Part Number: XC908AS60ACFU
• Description: MC68HC908AZ60A, MC68HC908AS60A Hcmos Microcontroller Unit Technical Data
• Manufacturer: Motorola Semiconductor Products

8.4.1 Accumulator (A)
8.4.2 Index register (H:X)
MC68HC908AZ60A — Rev 2.0
MOTOROLA
H:X
A
Reset:
Read:
Write:
Reset:
Read:
Write:
The accumulator is a general-purpose 8-bit register. The CPU uses the
accumulator to hold operands and the results of arithmetic/logic
operations.
The 16-bit index register allows indexed addressing of a 64K byte
memory space. H is the upper byte of the index register and X is the
lower byte. H:X is the concatenated 16-bit index register.
In the indexed addressing modes, the CPU uses the contents of the
index register to determine the conditional address of the operand.
The index register can also be used as a temporary data storage
location.
X = Indeterminate
Bit
15
0
Bit 7
14
0
Central Processor Unit (CPU)
13
Figure 8-3. Index register (H:X)
0
Figure 8-2. Accumulator (A)
6
12
0
11
0
5
10
0
Unaffected by reset
9
0
4
8
0
7
X
3
X
6
Central Processor Unit (CPU)
X
5
2
X
4
X
3
1
Technical Data
CPU registers
2
X
X
1
Bit 0
131
Bit
X
0