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EPSON
S1C88348/317/316/308 TECHNICAL HARDWARE
4 INITIAL RESET
Also, when using the initial reset by simultaneous
LOW level input into the input port, you should be
careful of the following points.
(1) During SLEEP status, since the time authoriza-
tion circuit is bypassed, an initial reset is
triggered immediately after a LOW level
simultaneous input value. In this case, the CPU
starts after waiting the oscillation stabilization
time and the SVD circuit initial sampling time
(when used with the mask option), following
cancellation of the LOW level simultaneous
input.
(2) Other than during SLEEP status, an initial reset
will be triggered 1–2 seconds after a LOW level
simultaneous input. In this case, since a reset
differential pulse (64/fOSC1 sec.) is generated
within the S1C883xx, the CPU will start even if
the LOW level simultaneous input status is not
canceled.
4.2 Initial Settings After Initial Reset
The CPU internal registers are initialized as follows
during initial reset.
Table 4.2.1 Initial settings
Register name
Code
Setting value
Data register A
Data register B
Index (data) register L
Index (data) register H
Index register IX
Index register IY
Program counter
Stack pointer
Base register
Zero flag
Carry flag
Overflow flag
Negative flag
Decimal flag
Unpack flag
Interrupt flag 0
Interrupt flag 1
New code bank register
Code bank register
Expand page register
Expand page register for IX
Expand page register for IY
A
B
L
H
IX
IY
PC
SP
BR
Z
C
V
N
D
U
I0
I1
NB
CB
EP
XP
YP
Undefined
0
1
01H
Undefined
00H
Bit length
8
16
8
1
8
*
Reset exception processing loads the preset
values stored in 0 bank, 0000H–0001H into the
PC. At the same time, 01H of the NB initial
value is loaded into CB.
Initialize the registers which are not initialized at
initial reset using software.
Since the internal RAM and display memory are
not initialized at initial reset, be sure to initialize
using software.
The respectively stipulated initializations are done
for internal peripheral circuits. If necessary, the
initialization should be done using software.
For initial value at initial reset, see the sections on
the I/O memory map and peripheral circuit
descriptions in the following chapter of this
Manual.