Specifications

ESS Technology, Inc. SAM0025A-062397 81
ES1879 DATA SHEET
REGISTERS
PRELIMINARY
Legacy Audio Interrupt Control (B1h, R/W)
Bit Definitions:
DRQ Control (B2h, R/W)
Bit Definitions:
Game-
compatible
IRQ
Enable IRQ ovf Ext
mode DMA cntr
Enable IRQ for
FIFO1 HE status
edge
x Audio 1 interrupt
7 6 5 43210
Bits Name Description
7 Game-com-
patible IRQ
Reserved for Compatibility mode. Leave zero
for Extended mode.
6 Enable
IRQ ovf Ext
mode DMA
cntr
Set high to receive interrupts for each over-
flow of the ES1879 DMA counter in Extended
mode.
5 Enable
IRQ for
FIFO1 HE
status edge
Set high to receive interrupts for FIFO Half-
Empty transitions when doing block I/O
to/from the FIFO in Extended mode.
4 – No function. The audio device activate bit
serves the purpose of enabling the interrupt
pin (PnP register 30h for LDN 1).
3:0 Audio 1
interrupt
Read-only. Decode the selected interrupt
number for the first audio interrupt as follows:
bit 3
bit 2 bit 1 bit 0 Audio 1 Interrupt
0 0 0 0 2, 9, all others
0 1 0 1 5
1 0 1 0 7
1 1 1 1 10
Game-
compatible
DRQ
Enable DRQ for
Extended mode
DMA
Enable DRQ
game compatible
DMA
x Audio 1 DRQ
7 6 5 43210
Bits Name Description
7 Game
compatible
DRQ
Reserved for Compatibility mode. Leave zero
for Extended mode.
6 Enable
DRQ for
Extended
mode DMA
1 = Enable DRQ outputs and DACKB inputs
for DMA transfers in Extended mode.
0 = Enable block I/O to/from the FIFO in
Extended mode.
5 Enable
DRQ game
compatible
DMA
Reserved for Compatibility mode. Leave zero
for Extended mode.
4 – No function. The DRQ lines always drive
(there is no enable). If neither bit 5 nor bit 6 is
set high, the first audio DRQ is always low.
The pull-down feature of DRQ pins in previous
parts was discontinued in the ES1879.
3:0 Audio 1
DRQ
Read-only. The selected DMA channel num-
ber for the first audio DMA channel are
decoded to set these bits as follows:
bit 3
bit 2 bit 1 bit 0 Audio 1 DRQ
0 1 0 1 0
1 0 1 0 1
1 1 1 1 3
0 0 0 0 all others