cs4239 Cirrus Logic, Inc., cs4239 Datasheet - Page 22

• Manufacturer Part Number: cs4239
• Description: Crystalclear? Ortable Isa Audio System Logic
• Manufacturer: Cirrus Logic, Inc.

(Hostload), the first four bytes are not needed;
therefore, the configuration data is only 19 bytes
long. The configuration data maps the many
functions of the logical devices to the physical
pins of the chip. Table 2 lists the Hardware Con-
figuration bytes. The detailed bit descriptions for
each byte follows. While the reserved bits are
NOTE:The first four bytes are exclusive to the E
* Currently not supported. Must be set to default values given in the table.
22
BYTE
11*
12*
13*
18*
10
14
15
16
17
19
20
21
22
23
1
2
3
4
5
6
7
8
9
Default
DDh
BBh
FCh
B9h
55h
00h
00h
03h
80h
00h
05h
20h
04h
08h
10h
80h
00h
00h
08h
48h
75h
10h
03h
This byte and the next byte specify hardware DRQ/DACKs tied to the DMAA-DMAC pins
Along with next two bytes - specify hardware interrupts tied to IRQA-IRQF pins
Misc. Configuration Bits: CDROM Interrupt Polarity, Key Disables, VCEN
DMA C/IRQ G Selection: Lower nibble = DMA C, Upper nibble = IRQ G
Alternate CDROM (Logical Device 4), ACDbase, Address length mask
Global Configuration Byte 2: EECS, AUX1R, 3DEN, DSPD1, PSH
Table 2. Hardware Configuration Data
IRQ C/D Selection: Lower nibble = C, Upper nibble = D.
IRQ A/B Selection: Lower nibble = A, Upper nibble = B.
DMA A/B Selection: Lower nibble = A, Upper nibble = B.
IRQ E/F Selection: Lower nibble = E, Upper nibble = F.
CDROM (Logical Device 4), CDbase, Address length
The first two bytes indicate that the E
Global Configuration Byte: IFM, VCF1, WTEN
2
PROM and are not used in the Hostload mode.
High byte for length of data in E
Low byte for length of data in E
Mono and DSP Port Control
and the 7th IRQ pin - IRQ G
RESERVED - Must be 0x04
RESERVED - Must be 0x08
RESERVED - Must be 0x10
RESERVED - Must be 0x48
E
E
2
2
PROM validation byte 1.
PROM validation byte 2
E
FM Volume Scaling
2
Code Base Byte
PROM Checksum
listed as "res" in the bit position (and must al-
ways be written as 0), "rbc" is used for
"reserved, backwards compatible" for bits that
were used on previous chips, but are no longer
required on this chip. These bits are read/wri-
table but should generally be set to 0 for
backwards compatibility.
Description
RESERVED
CrystalClear Portable ISA Audio System
2
2
2
PROM exists.
PROM
PROM
TM
CS4239
DS253PP2