MC68HC05P9ACDW FREESCALE [Freescale Semiconductor, Inc], MC68HC05P9ACDW Datasheet - Page 31

• Manufacturer Part Number: MC68HC05P9ACDW
• Description: HCMOS Microcontroller Unit
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Accumulator
Index Register
Stack Pointer
9-hc05cpu
MOTOROLA
Reset:
Reset:
Read:
Read:
Write:
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 and logic
operations.
The index register can be used for data storage or as a counter. In the
indexed addressing modes, the CPU uses the byte in the index register
to determine the effective address of the operand.
The stack pointer is a 16-bit register that contains the address of the next
stack location to be used. During a reset or after the reset stack pointer
instruction (RSP), the stack pointer is preset to $00FF. The address in
the stack pointer decrements after a byte is stacked and increments
before a byte is unstacked.
Freescale Semiconductor, Inc.
For More Information On This Product,
Bit
15
Bit 7
Bit 7
0
0
= Unimplemented
14
0
0
Go to: www.freescale.com
13
0
0
6
6
12
0
0
Figure 13. Index Register (X)
Figure 14. Stack Pointer (SP)
Figure 12. Accumulator (A)
CPU
11
0
0
5
5
10
0
0
Unaffected by reset
Unaffected by reset
9
0
0
4
4
8
0
0
7
1
1
3
3
6
1
1
5
1
2
2
4
1
3
1
1
1
CPU Registers
2
1
1
1
Bit 0
Bit 0
CPU
Bit
0
1
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