YMF724F
4. Interrupt Routing
DS-1 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-1 are routed as shown below.
PCI Audio
INTA#
INTA
SIEN=0, IMOD=1
SIEN=0, IMOD=0
IRQ
Sound Blaster Pro
IRQ5
IRQ7
SIEN=1, IMOD=*
Select Signal
ISA IRQ
IRQ9
SBIRQ[2:0]
IRQ10
IRQ11
SIEN=0, IMOD=1
SIEN=0, IMOD=0
IRQ
MPU401
SIEN=1, IMOD=*
SIEN, IMOD
Select Signal
SERIRQ#
SERIRQ
MPUIRQ[2:0]
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-1 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.
5. Digital Audio Interface
DS-1 only supports SPDIF output conforming to IEC958. The only supported Fs is 48 kHz. It can be
selectable from the Dolby Digital (AC-3) encoded data or the result of Digital Mixing.
January 14, 1999
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YAMAHA [ YAMAHA CORPORATION ]
