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YMF744B
February 3, 1999
-43-
2-2-4. SB IRQ Status
F8h: Interrupt Flag Register
Read Only
Default: 00h
b7 b6 b5 b4 b3 b2 b1 b0
- - - - - - - SBI
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 (R/W) MIDI Data port
MPUBase + 1h (R) Status Register port
MPUBase + 1h (W) Command Register port
portD7D6D5D4D3D2D1D0
+0h Data
+1h (W) Command
+1h (R)/DSR/DRR------
2-4. Joystick
JSBase (R/W)
portD7D6D5D4D3D2D1D0
+0h JBB2 JBB1 JAB2 JAB1 JBCY JBCX JACY JACX
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