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3 INSTRUCTION SET
DEC Mn
Source Format:
Operation:
OP-Code:
Type:
Clock Cycles:
Flag:
Description:
Example:
DEC SP
Source Format:
Operation:
OP-Code:
Type:
Clock Cycles:
Flag:
Description:
Example:
38
Decrement memory
DEC Mn
M(n
to n
)
M(n
to n
3
0
3
1 1 1 1 0 1 1 1 n
MSB
IV
7
C –
Set if a borrow is generated; otherwise, reset.
Z –
Set if the result is zero; otherwise, reset.
D –
Not affected
I –
Not affected
Decrements the contents of the data memory location addressed by Mn by 1.
DEC M0
Memory (00H)
1001
Memory (02H)
0000
Memory (0FH)
0001
C flag
1
Z flag
0
Decrement stack pointer
DEC SP
SP
SP - 1
1 1 1 1 1 1 0 0 1 0 1 1
MSB
VI
5
C –
Not affected
Z –
Not affected
D –
Not affected
I –
Not affected
Decrements the contents of the stack pointer by 1. This operation does not affect
the flags.
Memory (SP)
1011 0001
C flag
0
Z flag
1
) - 1
0
n
n
n
F70H to F7FH
3
2
1
0
LSB
DEC M2
1000
0000
0001
0
0
FCBH
LSB
DEC SP
1011 0000
0
1
EPSON
DEC M0FH
1000
1000
1111
1111
0001
0000
1
0
0
1
S1C6200/6200A CORE CPU MANUAL
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