6 2.
MPU
6-2
IC6
sN74Ls245N
RAM3,RAM4’
Connector
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Address
,cn
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74’-SOS"
Decoder
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gggger
1
M
R/W
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,
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5 2
MPU
Circuit
1.
Data
Bus
Do-D7
(Bi-Directional)
,
which
are
directly
connected
to
ROM,
RAM,
PIA,
ACIA
and
CRTC,
conducting
the
receipt
and
sending
of
the
data
to
MPU.
Through
IC6,
these
data
bus
signals
also
conducts
the
transaction
of
the
data
between
system
expansion
connector
I/F-l-I/F-6,
memory
expansion
connector
RAM
3,
RAM
4
and
MPU
data
bus.
6-2
MPU
Circuit
Figure
6-2
shows
the
MPU
circuit.
In
CRTC,
the
location
of
the
light
pen
is
connected
to
the
screen
address
information
then
outputted
to
MPU
through
CRTC
data
bus.
Summary of Contents for MB-6890
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Page 2: ...HITACHI PERSONAL COMPUTER MB 6890 SERVICE MANUAL ev O 30 1 2 1 ...
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