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YMF744B
February 3, 1999
-46-
4. Interrupt Routing
DS-1S supports three types of interrupts, interrupt signal on the PCI bus (INTA#), interrupt signal on the ISA
bus (IRQ[5,7,9,10,11]), and Serialized IRQ.
The IRQs on DS-1S are routed as shown below.
Sound Blaster Pro
MPU401
IRQ
SelectorSelector
IRQ
SBIRQ[2:0]
ISA IRQ
SERIRQ
MPUIRQ[2:0]
SIEN, IMOD
SIEN=0, IMOD=1
SIEN=0, IMOD=0
SIEN=1, IMOD=*
SIEN=0, IMOD=1
SIEN=0, IMOD=0
SIEN=1, IMOD=*
Select Signal
Select Signal
IRQ5
IRQ7
IRQ9
IRQ10
IRQ11
SERIRQ#
INTA#
INTA
PCI Audio
PCI Audio can only use INTA#, but the Sound Blaster Pro and MPU401 blocks of the Legacy Audio Block
can use any of the three protocols.
The protocol can be switched using 40-43h (Legacy Audio Control Register) of the PCI Configuration
Register.
4-1. Serialized IRQ
Serialized IRQ is a method to encode IRQs of 15 channels into one signal.
DS-1S provides the SERIRQ# pin to support Serialized IRQ.
Only one channel out of the 5 channels, IRQ5, IRQ7, IRQ9, IRQ10, and IRQ11, can be encoded into the
IRQ/Data frame of Serialized IRQ.
The IRQ channel is selected using 40h-43h (Legacy Audio Control Register) of the PCI Configuration
Register.