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Source Format:
Operation:
OP-Code:
Type:
Clock Cycles:
Flag:
Description:
Example:
Source Format:
Operation:
OP-Code:
Type:
Clock Cycles:
Flag:
Description:
Example:
MSB LSB
MSB LSB
C –
Z –
D –
I –
C –
Z –
D –
I –
38 EPSON S1C6200/6200A CORE CPU MANUAL
3 INSTRUCTION SET
DEC Mn
DEC SP Decrement stack pointer
Decrement memory
DEC Mn
M(n
3 to n0) ← M(n3 to n0) - 1
11110111n
3 n2 n1 n0 F70H to F7FH
IV
7
Set if a borrow is generated; otherwise, reset.
Set if the result is zero; otherwise, reset.
Not affected
Not affected
Decrements the contents of the data memory location addressed by Mn by 1.
DEC M0 DEC M2 DEC M0FH
Memory (00H) 1001 1000 1000 1000
Memory (02H) 0000 0000 1111 1111
Memory (0FH) 0001 0001 0001 0000
C flag 1 0 1 0
Z flag 0 0 0 1
DEC SP
SP ← SP - 1
111111001011 FCBH
VI
5
Not affected
Not affected
Not affected
Not affected
Decrements the contents of the stack pointer by 1. This operation does not affect
the flags.
DEC SP
Memory (SP) 1011 0001 1011 0000
C flag 0 0
Z flag 1 1