Service manual
PC-l600
Pin
Symbol In/
Out
Activ.
FU
l'ICtion
N,.
1
....
1
24
CKOS
I,
The
00
slg
nll
indiclte1i
that
the
CPU !
LH
58
.03) read timing
II
It
• low level
wh.n
not
writing, So, It mlV
pO$siblV
be
It
• tow level
when
not
reldlng,
.n
d It also may
not
matCh
th
e
2-80',
timing
during
dll.
Inpu~outPUt
of
the
5C7852
Internal dIIla.
To
prevent
these problems,
the
signll
goat
low
onlv
when
the
lH·5803
is
reading
the
memory
or
I/ O
II
created
with
fi
ve
lignl
l
(M
EO
,
MEl,
00,
CKOS,
an
"d BR05).
25
vee
- P
ower
supplV
(input
of
VGG
of
th'lynem).
,.
aND
-
POWIt
supplv
.
27
BAD
I,
See Pin No. 24.
28-30
0<>-02 In
/Ou
t 2-80
dIItl
bus.
31-35
03
-
07
D.n
When
the
sub
CPU outpUt
PI
(SlCB),
which is
len1
out
when
the
svstern.is oH,
illt
I high
I_I,
02-00
becom.low
,
thus
filling
the
level
of
the in
put
sinal during
systam-off81
02-00
are
inputs
also.
elD
Th.
em
line
of
the
SC7852
goes high when the 2-80
wlrl"
;
30
H
of
the
liD.
.-
36
I,
High
37
1M!'
I,
L~
The
signll
used
to
send
A33-
R
20
on
the
Z..aO
dall
bu
s.
It
goes
low
when
I
h.
2-80 re
lds
33H
of
the
110.
38 eL
"
L~
SyStem
r_t
input. When thll signal
illt
I
low
level,
it
forces
Al6A
to
high, A
15A
to
low,and
A1
4A
to
high.
39
AI3
I,
CPUaddreQA13.
""
AI'
I,
In
put
of
the
CPU address A 14 IInlignlflcanl).
41 DSA
Qu.
Not uMd.
.2
e
lKI
Qu,
When
the
SVStam
i.
on,
CL.2I.
I .....
ed
on
this
lin.
Ind
becomes
the
basic clock for
the
UART. A low
Is
on
this line
when
th.syltem
is
off.
43
KH
Qu,
H
ig
h
Oppollte
polarity
of
the
BREAK/ON key
input
i
lllnt
10
th
'lub
CPU.
44 A13A
Qu,
Opposlt.
polarity of
the
A 13 Input I.
tent.
45-47
AI4A
-
AI6A
Qu,
CIO
Iltched
02-00
output.
Also,
A16A
is
used for
separlting
the
~
select
ed
16
K8
m.mory
spac.
4000H-
7FFFH
(bank
3)
i
nto
two
benks.
48-60
lH
S1-
LH
S3
I,
L
,.
M.mory
Ml
leet
Ind
I
/O
seleet
s
ign
lis
from
the
SC7852
Ire
MInt
10
IIO
IS
of SI : and
51-53
KAO-K2
I,
L~
S2: lIil
the
gat.
arrav. The reason why
il
that
it
has
to
be
MIt
at
a high level
at
SVltem-off
..
the
5C7852
power
IIJpplV
Is
s
hut
off
when
thaly
ltem
is
off.
III
Wh.n
th'SVltem
is
on
but
not
In
a
_ak
ben.ry
condition
the
status
of
IIc
h
signal ac>PIln
on
SI,
52
,
53,
KO
, Kl ,
and
K2
.
121
All
Ire
high
whe
n
tha
svne
m
Is
off or a
weak
benary
I.
detected.
54-56
SI-S3
Qu,
L
,.
LHS1
-KA2
OUtpUtL
59-6
1
KO
-K2
Qu,
L,.
A
ll
er.
high
outpuU
when
th'IVltem"
off.
62
MEl
"
63
MEO
I,
See
pin
No.
24
.
..
00
I,
-3
1-