Korg RK-100 - Circuit Descriptions; CPU

7.
CIRCUIT
DESCRIPTIONS
The
seven basic
sections of the RK-100
are
(1}
the
micro-
(1)
CPU
computer CPU,
(2)
memory,
(3)
A-D converter.
(4)
input, IC6
(HD6301)
is an 8-bit
microcomputer
with internal
4K
|5)
display,
(6)
MIDI
data output,
and
(7)
power
supply. ROM
and
128#
RAM; it
has the following
four
kinds of
We are going
to simply explain as follows.
PORT.
Port
Term
Type
Furtction
Port
1
(P10-P17)
8-bit
1
P10-P15
P16
P17
Output
Output
Input
Scan address of program
indicator,
keyboard matrix
and shift
sw.
A-D converter
conversion start signal.
Fig-1
A-D converter
conversion completion
signal. Fig-2
Port
2
(P20-P24)
5-bit
H
Output
Input
Input
Output
1 Output
A-D converter address
signal. Fig-3
Selection
of internal or
external memory.
250kHz clock
signal
(8
times MIDI
clock frequency
31 ,25kHz)
Fig-4
1
A-D converter address signal.
Fig-5
MIDI signal.
Port
3
(P30-P37)
8-bit
P30-P37
Input/output
ports
A-D multiplex bus
(Low
order
8
bits of address
and
data bus).
Port
4
(P40-P47)
8-bit
P40-P43
P44-P47
Output
Output
pPD2764 address signal.
Selects
1C using data
bus (HC240, M58990,
mPD2746).
Fig-2 A/D Converter
Conversion Completion
Signal
O.lmsec O.lmsec
Fig-3
A/D Converter
Address Signal
Fig-4
Clock
Signal
0.2msec 0.2m$ec
Fig-5
A/D Converter Address
Signal
-
8
-