YMF740C Datasheet, PDF (24/44 Pages) List of Unclassifed Manufacturers – DS-1L

YMF740C
2. ISA Compatible Device
DS-1L contains the following functions to maintain the compatibility with the past ISA Sound Devices.
These devices are considered Legacy devices and the functions are referred to as Legacy Audio.
Legacy Audio is independent from PCI Audio and can be used simultaneously.
The configuration is set in the Legacy Audio Control Register in the PCI Configuration Register space.
Basically, these registers are configured by the BIOS.
Also, logical device IDs are assigned to the devices to support Plug and Play. Yamaha defines the following
logical IDs.
To control the device with the BIOS, the logical device IDs must be defined in the PnP BIOS extended ROM
space. The logical IDs are determined by how it is configured. IDs and configuration are as follows.
Logical Device ID
YMH0100
YMH0101
FM ^(*)
O
Functions used (Block)
MPU401
SB Pro ^(*)
O
O
Joystick
O
* The blocks pertain to the following.
FM:
Points to the FM synthesizer mapped to AdLibBase (0x0388).
SB Pro:
Points to the Voice Playback section only.
These devices are independent from each other, and can be Enabled/Disabled individually. However, both
AdLib and Sound Blaster must be disabled to disable the internal FM Synthesizer. Disabling just AdLib
only masks the access.
The driver by Yamaha supports only logical device ID, YMH0100. For YMH0101, use the driver provided
by Microsoft.
DS-1L supports PC/PCI protocol to emulate the DMA of SB Pro on the PCI. In addition, DS-1L supports
the old type of interrupts used by ISA.
The PCI-to-ISA bridge needs to support PC/PCI. IRQ is directly connected to the IRQ input pins on the
PCI-to-ISA bridge.
January 14, 1999
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