ES1371 Datasheet, PDF (8/37 Pages) List of Unclassifed Manufacturers – ENSONIQ AudioPCI 97 digital controller

ENSONIQ Proprietary Information
5. PCI Data Transfers
The internal control registers of the AudioPCI 97 Chip and the AC97 CODEC are accessed via 16 Long
Words in PCI direct I/O space. These registers are always read as 32 bit longwords but can be written as
bytes, words or longwords.
PCI bus mastering is used to transfer audio data between system memory and AudioPCI 97 internal
memory. The internal Cache Control Block and the PCI Interface control these transfers. Only burst
read/write transfers are allowed. All data transfers are 8 Long Word burst transfers.
5.1. Audio Read Transfers
The CCB requests a read data transfer from the PCI interface block (PCIB). The PCIB arbitrates for the
PCI bus and initiates an 8 long word read starting at the system address specified by the CCB in the read
request. When the data is acquired, the PCIB signals the CCB to begin moving the data to internal memory.
The CCB performs any byte alignment required and writes the data to the appropriate buffer in the internal
memory. The CCB will complete the current transfer request and then proceed to the next highest priority
request.
5.2. Audio Write Transfers
The CCB will first write up to 8 long words into the intermediate PCI buffer. The CCB will then request a
write transfer from the PCIB to main memory and specify the starting address of the transfer. The PCIB
arbitrates for the PCI bus and transfers 8 Long Words into system memory. Eight Long words will always
be transferred during this operation.
ENSONIQ Proprietary Information
ENSONIQ AudioPCI 97 Specification Rev 1.1 Oct 1, 1997
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