Yamaha LSI YMF744B Technical Manual page 20

YMF744B
b14..............SIEN: Serialized IRQ enable
DS-1S supports 3 types of interrupt protocols: PCI interrupt (INTA#), Legacy interrupt (IRQs) and
Serialized IRQ. The interrupt protocol is selected with IMOD and SIEN as follows.
The interrupt channels for IRQs and Serialized IRQ are determined by SBIRQ and MPUIRQ,. Only one
protocol can be used at once.
SIEN IMOD
0 0
0 1
1 *
b15..............LAD: Legacy Audio Disable
This bit disables the Legacy Audio block.
"0": Enables the Legacy Audio block
"1": Disables the Legacy Audio block
When this bit is set to "1", DS-1S does not respond to the I/O Target transaction for legacy I/O address on
the PCI bus.
42-43h: Extended Legacy Audio Control
Read / Write
Default: 0000h
Access Bus Width: 8, 16, 32-bit
b15 b14 b13
IMOD SBVER
b8................MAIM: MPU401 Acknowledge Interrupt Mask
This bit determine whether interrupt is asserted when the acknowledge, which is occurred by changing
MPU401 mode form default to UART, is returned.
"0": Interrupt is asserted when the acknowledge is returned.
"1": Interrupt is masked when the acknowledge is returned.
b[12:11] ......SMOD: SB DMA mode
These bits determine the protocol to achieve the DMAC(8237) function on the PCI bus.
"0": PC/PCI
"1": reserved
"2": Distributed DMA
"3" reserved
Interrupt protocol
Legacy interrupt (IRQs)
PCI interrupt (INTA#)
Serialized IRQ
b12 b11 b10 b9
SMOD - -
(default)
(default)
(default)
b8 b7 b6
MAIM - -
(default)
-20-
b5 b4 b3 b2
- - - -
February 3, 1999
b1 b0
- -