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DW-6000
port functions
are as
follows:
Port
A
(PA0~PA7): The
keyboard
matrix
and
switch
ma-
trix
input
port.
IC9 and
IC10
(4050)
are non-inverting buffers.
Port
B (PBO
—
PB3)
:
A
4-bit
output
port
for
switch matrix
row
control
signals.
Decoding
is
per-
formed by
IC11
(LS138) and IC12
(LS139),
which
have 12
outputs.
TXD, RXD:
Serial
I/O data terminals
for
MIDI
OUT
and
MIDI
IN, respectively.
MIDI
IN/OUT
and
MIDI
THRU
circuits
consist of the
photo-
coupler
PCI
(TLP552) and IC14
(LS09)
AND
circuit.
Port C:
The two
bits
handled
by
PC5
and
PC6
are
for
the tape
interface
output
terminal
(TO
TAPE),
with
Q1
(C2785) and
C7
(0.047ju)
used
for
conversion
to
audio
level.
PC7
is
for
the tape interface input terminal
(FROM
TAPE),
with
1
C
1
6
(4558),
DB4
(MC931), and
DB5
(MC921)
used
for
wave
shaping
from
audio
level
to
square wave.
AN0~AN3:
A/D
converter input terminal
for input of
joystick x, y,
tune
control,
and
slider
variable
resistors.
1/2
I
Cl 7 (4558) determines
joystick
center
value.
AD0~AD7:
This terminal
is
for
the lower
8-bit
address
bus
and
data
bus.
The
lower
address bus
is
latched
by
IC6 (LS373).
AB8~AB15:
Upper
address
output
port.
Performs
ROM
and
RAM
addressing
with
AB8
^
AB12
and
chip
selection
with
AB13
~
AB15.
IC2 (2764)
is
an
EPROM
chip containing the data
and
system program
for
operating the
CPU
(IC1
(/iPD7811)).
IC3
(HM-6116)
is
RAM
for storage
of
user
created
sound
data,
protected
by
the
CR2032-F1
backup
battery.
IC7
(H374) works
as
an
interface
between
CPU1
and
CPU2.
IC18 (S-8054HN)
is
a
3-terminal 1C for
system
resetting:
IC17 (4558) and
Q2,
Q3
(A1175)
are
used
for
MIDI power
supply;
at
the
same
time
this
is
input to the
CPU
AN4
terminal
for leading
edge
detection.
(2)
KLM-654:
This
board
contains the
DWGS
basic
system.
The
purpose
of
this
system
is
to get pitch
and waveform
data
from
the
CPU
bus
and
output
a
cyclic
(repetitive)
waveform
of
con-
stant
amplitude.
Oscillator
operation
The PAI
(phase angle
increment)
value
and
PAR
(phase
angle
register)
value
are
added and
the
result
is
stored again
in
the
PAR. The
PAR
value
is
used
as
the
wave
table ad-
dress.
The wave
table stores different
harmonic
configura-
tion data for
each octave
on
the
keyboard.
IC29
(MB64H129)
performs
the processing
needed
to use
the
PAR
value
as
the
wave
table address.
Finally,
data read
from
the
wave
table
is
converted
to
an
analog
waveform
by
a
D/A
converter.
Time
division
multiplexing enables dual
oscillator
6-voice
sound
source
capability.
(Maximum
simultaneous output of
this
system
is
8
voices
x
2
oscillators.)
Note: Given
a
sampling frequency
of
50 kHz, PAI
data
N
=
2
1
8
x f/50
x
10
3
(where
f
is
the
pitch
frequency)
is
rounded
to an
integer value for
N
and
converted
to a
hexadecimal number.
CPU BUS
IC32
(MB62H133)
......
.74LS189X
10
IC33-IC37, IC39-IC43
IC32 (62H133)
IC31
(64H129)
.64
K
ROM
IC29,
IC30
.0
AC-08
HC138
+
4066
+
072
The
main
LSI
chips
are
the
CMOS
gate array
IC31
(MB-
64H129)
and
IC32
(MB62H133),
the wave-table
256K
mask
ROM
IC29 and IC30 (HN613256),
the ten
TTL
64-
bit
RAM
chips
for
PAI
& PAR
(IC33~IC37, IC39~IC43;
S189),
the
8-bit
D/A
converter
IC28 (D AC-08), decoder
chips
IC38,
IC44
(LS244),
IC16
(LS175), IC14, IC15
(LS138),
as
well
as
S/H
analog switches
(IC11~IC13;
4066) and
OP
AMPS
(IC5-IC10;
072).
IC32
(MB62H133)
is
a
64-pin LSI with
about
800
gates
handling
major
aspects of the
system
including the
CPU
interface,
timing generation,
and
adder.
-
27
-
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