Yamaha YMF744B (DS-1S) Stereo System User Manual


 
YMF744B
February 3, 1999
-19-
b4................MIEN: MPU401 IRQ Enable
This bit enables the interrupt service of MPU401, when LAD is set to “0” and MEN is set to “1”.
MPU401 generates an interrupt signal when it receives any kind of MIDI data from the RXD pin.
“0”: The MPU401 block can not use the interrupt service.
“1”: The MPU401 block can use interrupt signals determined by the MPUIRQ bits. (default)
b5................I/O: I/O Address Aliasing Control
This bit selects the number of bits to decode for the I/O address of each block.
“0”: 16-bit address decode
“1”: 10-bit address decode (default)
b[7:6] ..........SDMA: Sound Blaster DMA-8 Channel Select
These bits select the DMA channel for the Sound Blaster Pro block.
“0”: DMA ch0
“1”: DMA ch1 (default)
“2”: reserved
“3”: DMA ch3
b[10:8] ........SBIRQ: Sound Blaster IRQ Channel Select
These bits select the interrupt channel for the Sound Blaster Pro block.
“0”: IRQ5 (default)
“1”: IRQ7
“2”: IRQ9
“3”: IRQ10
“4”: IRQ11
“5” - “7”: reserved.
b[13:11] ......MPUIRQ: MPU401 IRQ Channel Select
When MIEN is set to “1”, these bits select the interrupt channel for the MPU401 block.
“0”: IRQ5
“1”: IRQ7
“2”: IRQ9 (default)
“3”: IRQ10
“4”: IRQ11
“5” - “7”: reserved
Same interrupt channels can be assigned to SBIRQ and MPUIRQ.