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CHAPTER 2: POWER SUPPLY AND INITIAL RESET
2.2.2 Simultaneous low input to terminals K00–K03
Another way of executing initial reset externally is to input a low signal simultaneously to the input ports
(K00–K03) selected with the mask option.
Since this initial reset passes through the noise reject circuit, maintain the specified input port terminals at
low level for at least 1.5 msec (when the oscillation frequency f
tion. The noise reject circuit does not operate immediately after turning the power on until the oscillation
circuit starts oscillating. Therefore, maintain the specified input port terminals at low level for at least 1.5
msec (when the oscillation frequency f
Table 2.2.2.1 shows the combinations of input ports (K00–K03) that can be selected with the mask option.
When, for instance, mask option 2 (K00∗K01∗K02∗K03) is selected, initial reset is executed when the
signals input to the four ports K00–K03 are all low at the same time. When 3 or 4 is selected, the initial
reset is done when a key entry including a combination of selected input ports is made.
Further, the time authorize circuit can be selected with the mask option. The time authorize circuit checks
the input time of the simultaneous low input and performs initial reset if that time is the defined time (1
to 2 sec) or more.
If using this function, make sure that the specified ports do not go low at the same time during ordinary
operation.
2.2.3 Internal register at initial resetting
Initial reset initializes the CPU as shown in
Table 2.2.3.1.
The registers and flags which are not
initialized by initial reset should be initial-
ized in the program if necessary.
In particular, the stack pointers SP1 and SP2
must be set as a pair because all the inter-
rupts including NMI are masked after
initial reset until both the SP1 and SP2 stack
pointers are set with software.
When data is written to the EXT register,
the E flag is set and the following instruc-
tion will be executed in the extended
addressing mode. If an instruction which
does not permit extended operation is used
as the following instruction, the operation
is not guaranteed. Therefore, do not write
data to the EXT register for initialization
only.
Refer to the "S1C63000 Core CPU Manual"
for extended addressing and usable
instructions.
12
is 32.768 kHz) after oscillation starts.
OSC1
Table 2.2.2.1 Combinations of input ports
1
Not use
2
K00∗K01∗K02∗K03
3
K00∗K01∗K02
4
K00∗K01
Name
Data register A
Data register B
Extension register EXT
Index register X
Index register Y
Program counter
Stack pointer SP1
Stack pointer SP2
Zero flag
Carry flag
Interrupt flag
Extension flag
Queue register
Name
RAM
Display memory
Other pheripheral circuits
EPSON
is 32.768 kHz) during normal opera-
OSC1
Table 2.2.3.1 Initial values
CPU core
Symbol
Number of bits
A
4
B
4
EXT
8
X
16
Y
16
PC
16
SP1
8
SP2
8
Z
1
C
1
I
1
E
1
Q
16
Peripheral circuits
Number of bits
4
4
–
∗ See Section 4.1, "Memory Map".
S1C63358 TECHNICAL MANUAL
Setting value
Undefined
Undefined
Undefined
Undefined
Undefined
0110H
Undefined
Undefined
Undefined
Undefined
0
0
Undefined
Setting value
Undefined
Undefined
∗
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