D63GS NEC, D63GS Datasheet - Page 12

• Manufacturer Part Number: D63GS
• Description: Search -----> UPD63GS
• Manufacturer: NEC

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2.8 Arithmetic and Logic Unit (ALU): 4 Bits
manipulations with priority given to logical operations.
2.9 Flags
2.9.1 Status flag (F)
12
Operand Value of STTS Instruction
The arithmetic and logic unit (ALU), which refers to an arithmetic circuit consisting of 4 bits, executes simple
Pin and timer statuses can be checked by executing the STTS instruction to check the status flag.
The status flag is set (to 1) in the following cases.
• If the condition specified with the operand is met when the STTS instruction has been executed
• When STANDBY mode is canceled.
• When the cancelation condition is met at the point of executing the HALT instruction. (In this case, the system
Conversely, the status flag is cleared (to 0) in the following cases:
• If the condition specified with the operand is not met when the STTS instruction has been executed.
• When the status flag has been set (to 1), the HALT instruction executed, but the cancelation condition is not
b
0
1
3
is not placed in STANDBY mode.)
met at the point of executing the HALT instruction. (In this case, the system is not placed in STANDBY mode.)
Either of the combinations
of b
b
0
0
1
1
2
2
, b
1
, and b
Table 2-1. Conditions for Status Flag (F) to be Set by STTS Instruction
b
0
1
1
0
1
0
above.
b
0
1
0
1
0
High level is input to at least one of K
High level is input to at least one of K
High level is input to at least one of K
The down counter of the timer is 0.
High level is input to at least one of S
[The following condition is added in addition to the above.]
Condition for Status Flag (F) to be Set
I
I
I
0
pins.
pins.
pins.
and S
1
pins.
PD63, 63A, 64