Korg DDM-110 Service Manual page 12

CPU Terminal Function
Pin Term
Name
Type Function
52 VCC
Power supply input
Input Diode OR circuit constructed with VDD and VBATT
26 VSS
Power supply input Input Applies 0V (GND)
21 CNVSS CNVSS input
Input Connects to VSS
22 RESET
RESET input
Input
Resets when level goes to low for 2jus or more; power
on/off detection.
23 XIN
Clock input Input Operates with 4MHz ceramic oscillator connected
between XIN and XOUT.
25 XOUT
Clock output Output Output for internal clock generator. This output is
converted to 250kHz by IC7 (74HC393) and used for
MSM6235 clock.
18 CNTR
Timer input Input Input for clock signal from external device or internal
tempo oscillator circuit. Produces basic timing for
DDM tempo; also used during tape interface input.
19 INT Interrupt input Input
For start/stop control. Start — low; Stop - high.
10-17 P00-P07
I/O port P0
Input &
output
An 8-bit I/O port used as data bus.
35-42
6-8
P10-P17
P20-P22
Output port PI
Output port P2
Output
Output
Address bus output port. A(0)—A(10).
As above.
2-5 P23-P26 I/O port P2 Input &
output
MCS, MWE, RYWE, KSCN
1
P27
Output port P2 Output
Outputs high pulse when start switch turns on.
Controls tempo oscillator circuit.
43-50 P30-P37
Output port P3 Output
P30—P33 4 bits control LED display. P34 1 bit is for
LED clock. P35 1 bit controls tape interface input
phase. P36—P37 are for tape interface output and P37
is for handclaps trigger out.
27-30 R0-R3
Input port R Input
R0 1 bit is for tape interface position detection. R1
is high level. R2 detects whether anything is plugged
into the TRIG OUT jack.
Note; Observation of the R port waveform will show
an output signal in time with the address signal.
However, in this unit a diode is employed and these are
only used as inputs. '
34
RESET OUT Reset output Output Reset signal output for MSM6235.
2) Memory Section
This RAM (16k bit CMOS Random Access Memory HM
6116) is used, via the CPU, for reading and writing rhythm
patterns and performance sequences, etc.
This data is backed up by a battery. Data will be lost if the
battery has not been put in or if it runs low. In such cases,
load data from the data tape, using the tape interface.
In addition, the power supply circuit C2 capacitor (47
fxf!
16V RBLL) is used for short-term memory backup. If
replacement is necessary, be sure to use the same type,
having low leakage current.
The 6235RS is an LSI with PCM encoded recordings of
instrument sounds and a D/A converter with 8-bit data
bus interface, all on a single chip. Under CPU control,
this can produce up to four sounds simultaneously. The
DDM units each use two of these LSI chips so they can
generate up to eight sounds at once.
Notel: On the DDM-110, the hi-hat (HH) open and
closed sounds cannot be sounded at the same time,
they both use the same terminal; the same is true
for the snare and rimshot sounds.
On the DDM-220, the timble and woodblock can¬
not be sounded together; the same is true for the
hi-agogo and lo-agogo.
Note 2: The MSM6235 chip version number is different
for the DDM-110 and DDM-220. Be careful
not
to
confuse the two when replacing this part.
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