ENSONIQ Proprietary Information

ENSONIQ Proprietary Information

ENSONIQ AudioPCI 97 Specification Rev 1.1

Oct 1, 1997

6

4.11. Internal Memory

There are two separate sections of memory in AudioPCI 97. One section is allocated as a cache for the

playback and record channels and also as a FIFO for the UART. The other section is allocated to the

Sample Rate Converter module and is used as a cache for sample rate conversion and also as control

register space for the playback and record channels in the sample rate converter.

The internal memory for the sound cache in AudioPCI 97 is organized as 4 blocks of 64 bytes each. Each

block is divided into 4 pages of 16 bytes each (4 longwords). Memory can be accessed as longwords only.

In order to access a specific page of memory the memory page register must first be setup for the specific

page to be accessed. The first three blocks of memory contain the 3 circular buffers for the 2 playback

channels and the record channel. The last block contains the frame information for the playback and record

channels and also includes the UART FIFO. The memory block and page organization is shown below :

Block

Page

Higher

Address

Lower

0 - DAC 1

0000

DAC1 sample bytes 15 - 0

Lower half buffer

0001

DAC1 sample bytes 31 - 16

0010

DAC1 sample bytes 47 - 32

Upper half buffer

0011

DAC1 sample bytes 63 - 48

1 - DAC2

0100

DAC2 sample bytes 15 - 0

Lower half buffer

0101

DAC2 sample bytes 31 - 16

0110

DAC2 sample bytes 47 - 32

Upper half buffer

0111

DAC2 sample bytes 63 - 48

2 - ADC

1000

ADC sample bytes 15 - 0

Lower half buffer

1001

ADC sample bytes 31 - 16

1010

ADC sample bytes 47 - 32

Upper half buffer

1011

ADC sample bytes 63 - 48

3 - Frame/UART

1100

DAC1, DAC2 frame information (see register descriptions)

1101

ADC frame information (plus 2 open longwords)

1110

UART fifo (only bits 8 - 0 of each longword are used)

1111

UART fifo