mc68hc912bc32 Freescale Semiconductor, Inc, mc68hc912bc32 Datasheet - Page 60

• Manufacturer Part Number: mc68hc912bc32
• Description: M68hc12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Central Processor Unit (CPU)
3.3 CPU Registers
This section describes the CPU registers.
3.3.1 Accumulators A and B
Accumulators A and B are general-purpose 8-bit accumulators that contain operands and results of
arithmetic calculations or data manipulations.
3.3.2 Accumulator D
Accumulator D is the concatenation of accumulators A and B. Some instructions treat the combination of
these two 8-bit accumulators as a 16-bit double accumulator.
60
Reset:
Read:
Write:
Bit 15
(A7)
D15
(A6)
D14
14
The LDD and STD instructions can be used to manipulate data in and out
of accumulator D.
Reset:
Reset:
Read:
Read:
Write:
Write:
D13
(A5)
13
Bit 7
Bit 7
A7
B7
D12
(A4)
12
D11
(A3)
11
A6
B6
6
6
M68HC12B Family Data Sheet, Rev. 9.1
Figure 3-4. Accumulator D (D)
Figure 3-2. Accumulator A (A)
Figure 3-3. Accumulator B (B)
D10
(A2)
10
A5
B5
5
5
(A1)
D9
9
Unaffected by reset
NOTE
Unaffected by reset
Unaffected by reset
(A0)
A4
B4
D8
4
4
8
(B7)
D7
7
A3
B3
3
3
(B6)
D6
6
A2
B2
(B5)
2
2
D5
5
(B4)
D4
4
A1
B1
1
1
(B3)
D3
3
Freescale Semiconductor
Bit 0
Bit 0
A0
B0
(B2)
D2
2
(B1)
D1
1
Bit 0
(B0)
D0