The CPU12 Microprocessor Core

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The CPU12 Microprocessor Core

• Lecture L2.1

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Reference
S12CPUV2 Reference Manual S12CPUV2.pdf (in .zip
file)
Print out Appendix A Instruction Reference It
will answer all questions concerning
HCS12 instructions and addressing modes
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Introducing the CPU12

• The CPU12 Registers
• CPU12 Addressing Modes
• CPU12 Instructions

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The 68HC12 Registers
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Condition Code Register
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A
c
c
u
m
u
l
a
t
o
r

A

A
c
c
u
m
u
l
a
t
o
r

B

A
B
D
A
c
c
u
m
u
l
a
t
o
r

D
The 68HC12 Accumulators
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I
n
d
e
x

r
e
g
i
s
t
e
r

X
X
I
n
d
e
x

r
e
g
i
s
t
e
r

Y
Y
Index Registers, X and Y
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S
t
a
c
k

P
o
i
n
t
e
r
S
P
Stack Pointer, SP
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Introducing the CPU12

• The CPU12 Registers
• CPU12 Addressing Modes
• CPU12 Instructions

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Pre-decrement indexed addressing
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Using X as a stack pointerfor a data stack
LDY 2,X will pop 1234 into Y
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MOVW 0,X,2,-X
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LDD 0,XMOVW 2,X,0,XSTD 2,X
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MOVW 2,X,2,-X
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Introducing the CPU12

• The CPU12 Registers
• CPU12 Addressing Modes
• CPU12 Instructions

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Load Accumulator A
1 LDAA
Addressing Modes 2 00004000
ORG 4000 3 4000 86 35
LDAA 35 4 4002
96 A3 LDAA A3 5
4004 B6 5678 LDAA
5678 6 4007 A6 03
LDAA 3,X 7 4009 A6 E9 38
LDAA -200,Y 8 400C A6 F2
1234 LDAA 1234,SP 9
4010 A6 E7 LDAA
D,X 10 4012 A6 EB 2345
LDAA 2345,Y
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1 LDAA
Addressing Modes 2 00004000
ORG 4000 3 4000 86 35
LDAA 35 4 4002
96 A3 LDAA A3 5
4004 B6 5678 LDAA
5678 6 4007 A6 03
LDAA 3,X 7 4009 A6 E9 38
LDAA -200,Y 8 400C A6 F2
1234 LDAA 1234,SP 9
4010 A6 E7 LDAA
D,X 10 4012 A6 EB 2345
LDAA 2345,Y
200 C8 11001000 9-bit 011001000 2s
comp 100111000 138
11101001 E9
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1 LDAA
Addressing Modes 2 00004000
ORG 4000 3 4000 86 35
LDAA 35 4 4002
96 A3 LDAA A3 5
4004 B6 5678 LDAA
5678 6 4007 A6 03
LDAA 3,X 7 4009 A6 E9 38
LDAA -200,Y 8 400C A6 F2
1234 LDAA 1234,SP 9
4010 A6 E7 LDAA
D,X 10 4012 A6 EB 2345
LDAA 2345,Y
11110010 F2
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1 LDAA
Addressing Modes 2 00004000
ORG 4000 3 4000 86 35
LDAA 35 4 4002
96 A3 LDAA A3 5
4004 B6 5678 LDAA
5678 6 4007 A6 03
LDAA 3,X 7 4009 A6 E9 38
LDAA -200,Y 8 400C A6 F2
1234 LDAA 1234,SP 9
4010 A6 E7 LDAA
D,X 10 4012 A6 EB 2345
LDAA 2345,Y
11100111 E7
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1 LDAA
Addressing Modes 2 00004000
ORG 4000 3 4000 86 35
LDAA 35 4 4002
96 A3 LDAA A3 5
4004 B6 5678 LDAA
5678 6 4007 A6 03
LDAA 3,X 7 4009 A6 E9 38
LDAA -200,Y 8 400C A6 F2
1234 LDAA 1234,SP 9
4010 A6 E7 LDAA
D,X 10 4012 A6 EB 2345
LDAA 2345,Y
11101011 EB
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