CS4235 Datasheet, PDF (12/94 Pages) Cirrus Logic – CrystalClear Low Cost ISA Audio System

CS4235
CrystalClear ^TM Low Cost ISA Audio System
GENERAL DESCRIPTION
This device is comprised of six physical devices
along with Plug-and-Play support for one addi-
tional external device. The internal devices are:
Windows Sound System Codec
Sound Blaster Pro Compatible Interface
Game Port (Joystick)
Control
MPU-401
FM Synthesizer
The external device is:
IDE CDROM
On power up, this part requires a RESDRV sig-
nal to initialize the internal configuration. When
initially powered up, the part is isolated from the
bus, and each device supported by the part must
be activated via software. Once activated, each
device responds to the resources given (Address,
IRQ, and DMA channels). The devices listed
above are grouped into five logical devices, as
shown in Figure 1 (bracketed features are sup-
ported, but typically not used). The five logical
devices are:
LOGICAL DEVICE 0:
Windows Sound System Codec (WSS Codec)
Adlib/Sound Blaster-compatible Synthesizer
Sound Blaster Pro Compatible Interface
LOGICAL DEVICE 1: Game Port
LOGICAL DEVICE 2: Control
LOGICAL DEVICE 3: MPU401
LOGICAL DEVICE 4: CDROM
Logical Device 0 consists of three physical de-
vices. The WSS Codec and the Synthesizer are
grouped together since the original Windows
Sound System card expected an FM synthesizer
if the codec was present. The Sound Blaster Pro
Compatible interface, SBPro, is also grouped to
allow the WSS Codec and the SBPro to share
Interrupts and DMA channels. The WSS Codec,
FM synthesizer, and the SBPro compatible de-
vices are internal to the part.
Logical Device 1 is the Game Port that supports
up to two joystick devices.
Logical Device 2 is the Control device that sup-
ports global features of the part. This device uses
I/O locations to control power management,
joystick rate, and PnP resource data loading.
Logical Device 3 is the MPU-401 interface. The
MPU-401 MIDI interface includes a 16-byte
FIFO for data transmitted out the MIDOUT pin
and a 16-byte FIFO for data received from the
MIDIN pin.
Logical Device 4 supports an IDE CDROM de-
vice. Although this logical device is listed as a
CDROM, any external device that fits within the
resources listed above may be substituted. This
interface, is generic and can support devices us-
ing 1 to 127 I/O locations for the base address, 1
to 8 I/O locations for the alternate base address,
an interrupt, and a DMA channel.
ISA Bus Interface
The 8-bit parallel I/O and 8-bit parallel DMA
ports provide an interface which is compatible
with the Industry Standard Architecture (ISA)
bus. The ISA Interface enables the host to com-
municate with the various functional blocks
within the part via two types of accesses: Pro-
grammed I/O (PIO) access, and DMA access.
A number of configuration registers must be pro-
grammed prior to any accesses by the host
computer. The configuration registers are pro-
grammed via a Plug-and-Play configuration
sequence or via configuration software provided
by Cirrus Logic.
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