Casio CZ-1 - Page 88

(3)
SUB
CPUc£>MAIN
CPU.
In
tht
same
procedures
as
stated
in tht
item
(2),
MAIN
CPU
sends
"Request
Command"
that
inquires
SUB
CPU
to
transmit
data.
(5)
SUB
CPU
puts
data
on
data
bus
DSO
-
DS7
and
sets
the
data
in
Latch
4
by
signal
W1.
SUB
CPU
then
presets
F/F
2
by
pulse
*4.
causing
signal
X896
to
be
entered
in
MAIN
CPU.
Acknowledging
that
data
is set
in
Latch
4
by
signal
X896,
MAIN
CPU
generates
clock
pulse V.
causing
data
from
SUB
CPU
to
be
put
on
MAIN
CPU
data
bus
DO
-
D7.
(4)
After
receiving
data,
MAIN CPU
sends
SUB
CPU
an
interrupt
signal
from
terminal
PB2,
and by
interrupt
signal,
SUB
CPU
confirms
that
the
data
is
received
by
MAIN
CPU.
Repeating
the
above
procedures
(f)~
®
SUB
CPU
sends
the
next
data
to
MAIN
CPU.
Dummy
data to ot
ntrata
signal
Rtqunt
Command
1
Latch 2
y«aqut»t
Command
)(
IT
A
x
SYC
n
n
n n
U<eh4
"^""lit
data
X
2nd
data
//
X
Lait
data
MAIN
CPU
n
PB2
M
n
n
n
)
n_
X898
|
|
n
n
n )
n
((
CONT
|
L
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