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and
more
about Sharp
PC-1500
at
http://www.PC-1500.info
4-2.
PC-1500
4-2-1. Outline
(j)
CPU
T he 1.H5801
CMOS
8-bit
Microprocessor
is
used.
As
it
is
operated by
the
clock
freq uency of 2.6M Hz from
the
crystal oscillator.
its
internal
machine
cycle
is
I
.3M
Hz.
BFI
........... Depression
of the
@!~
key turns
it
to
high
level
so
that
YCC
is
supplied
from
BFO.
INO~I
N7
......
Input
port
for
other
than the
@
key.
DO~
D7 .
....... Bidirectional
dat<t
bus
which
is
used
to
write tmd
read data
to/
from
the
external
rncrnory.
DO: I.SB
07:
MS
B
ADO·vADl
5
...
.
Address
bus.
ADO:
LSB
ADl5:
MSB
XLO.
XU
......
Ex
ternal crystal connection terminals. throuJ;h which
the
2.6MHz
crystal
is
connected.
(j)
110 PC
XLO:
Input
XI.I
:
Output
Either
L H58
10
or
l..H58
1
I
is
used.
The
same
chip
is
used fo
r
l/
Oof
CE-
150.
CE-153.
a
nd CE-1
58.
PAONPA7 .
..
.
.
Key
strC
>IJc
output
Pll7
. . . . .
.
.
. .
.
.
@
key
inpm
ADO~·J.
A0
1
2~13.
Dtv)EI
......
Address
of
1/
0 port
is
set.
within
FOOOH
to
FOOFH
of the
MEI
area.
0
Timer IC
µ PD
1990AC
is
used and
connected
with
the
32.768kH
z
crystal.
©
Chip
select
decoder
It
consists
of
two chips
of
TC4011 I39F
and
TC40H
I
38F
and it
is
used
to
select chip
by
means
of
so~4.
S6.
S7.
2Y2
and
2Y3.
F
or
more
details. refer
to
"Chip
select
circuit".
<D
Display chip
Because
4-bit
SC882G
is
used
.
chip
I
is
used in pair
with
chip
3
a
nd
chip
2
with chip
4.
Select
signal
is commonly
used
hy
chip
I and
chip
3 or
chip
2
and
chip 4.
Data
hus
is
therefore divided into
DO·vOJ
a
nd
04-
07
in order
to handle
c
ompatible
with
the
8-
hit
RAM.
Address
is
within
7600
H
to
77FFH of
the
MEO area and
is
used fo
r
the
fixed
variable
area.
in
addit
ion
10·1
hc
di:>play
buffer.
©System
ROM
It
is
the
PC-1500
system
program residing RO
M
fo
r
which
the
8-bit X
16K
S
C61328F
is
used
.
Address is
within
COOO
H to FFFFH
of
the
MEO
area.
0
System RAM
Because
the
4-bit
X
I
K
bytes
TC55
14
is used
in
a
pair.
the
data
bus is
divided
imo
twoof
DO-
DJ
and
D4-
D7
and
the
select
signal
S7 is
commonly
shared
so
as
to be
compatible with the
8-bit
RAM.
Address
is
within 7800H
to
7Bl'FH of
the MEO
a
rea
which is
used
for the system
memory
area a
nd
fo
r
the
fixed
variable
area.
89
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