Instruction manual

8
TURBOchannel Dual SCSI ASIC
The TURBOchannel Dual SCSI ASIC interfaces the TURBOchannel using
the NCR 53C94 Advanced SCSI Controller in the 300/400/500 models and the
53CF94-2 Advanced SCSI Controller in the 600/700/800/900 models.
• 300 models communicate through channel A only
• 400/500/600/700/800/900 models communicate through two channels, channel
A and Channel B
In the following sections:
• A DMA read operation refers to a read operation from system main memory
• A DMA write operation refers to a write operation to system main memory.
• A DMA transmit operation refers to a transmission of data to the 53C94 or
53CF94-2.
• DMA receive operation refers to a receive of data from the 53C94 or
53CF94-2.
This chapter covers the following topics:
• TURBOchannel dual SCSI address map (Section 8.1)
• Internal registers (Section 8.2)
• 53C94 registers (Section 8.3)
• 53CF94-2 registers (600/700/800/900 Models) (Section 8.4)
• DMA buffers (Section 8.5)
TURBOchannel Dual SCSI ASIC 8–1