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YMF744B
2-2-4. SB IRQ Status
F8h: Interrupt Flag Register
Read Only
Default: 00h
b7
b6
b5
-
-
-
b0................SBI: SB Interrupt Flag
This bit indicates that the SB DSP occurs the interrupt. This bit is read only. Thus, read the SB DSP
read port to clearing the interrupt and this bit. Then, the value of the read port is invalid.
2-3. MPU401
This block is for transmitting and receiving MIDI data. It is compatible with UART mode of "MPU401".
Full duplex operation is possible using the 16-byte FIFO for each direction, transmitting and receiving.
The following shows the MPUBase I/O map for MPU401.
MPUBase
MPUBase + 1h
MPUBase + 1h
port
D7
+0h
+1h (W)
+1h (R)
/DSR
2-4. Joystick
JSBase
(R/W)
port
D7
+0h
JBB2
JACX...
Joystick A, Coordinate X
JACY...
Joystick A, Coordinate Y
JBCX...
Joystick B, Coordinate X
JBCY...
Joystick B, Coordinate Y
JAB1...
Joystick A, Button 1
JAB2...
Joystick A, Button 2
JBB1...
Joystick B, Button 1
JBB2...
Joystick B, Button 2
b4
b3
b2
-
-
-
(R/W)
MIDI Data port
(R)
Status Register port
(W)
Command Register port
D6
D5
D4
Command
/DRR
-
-
D6
D5
D4
JBB1
JAB2
JAB1
b1
b0
-
SBI
D3
D2
Data
-
-
D3
D2
JBCY
JBCX
-43-
D1
D0
-
-
D1
D0
JACY
JACX
February 3, 1999
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