LSI SYM22801 - Manual (Page 13)

Interface Descriptions 1-3
1.3 Interface Descriptions
This section provides a more detailed explanation about the PCI
Interface, The SCSI Interface, and Ultra SCSI.
1.3.1 The PCI Interface
PCI is a high-speed standard local bus for interfacing a number of I/O
components to the processor and memory subsystems in a high end PC.
The PCI functionality for the SYM22801 is contained within the Symbios
SYM53C876 PCI to Ultra SCSI I/O Processor chip. The SYM53C876
connects directly to the PCI bus and generates timing protocol in
compliance with the PCI specification.
The PCI interface operates as a 32-bit DMA bus master. The connection
is made through the edge connector J1 (see Figure 2.1). The signal
definitions and pin numbers conform to the PCI Local Bus Specification
Revision 2.1 standard. The SYM22801 conforms to the PCI universal
signaling environment for a 5 V or 3.3 V PCI bus.
1.3.2 The SCSI Interface
The SCSI functionality for the SYM22801 is contained within the
Symbios SYM53C876 PCI-Ultra SCSI I/O Processor chip. The
SYM53C876 connects directly to the two SCSI buses and generates
timing and protocol in compliance with the SCSI standard.
The SCSI interfaces on the SYM22801 operates as 16-bit, synchronous
or asynchronous, single-ended bus, and support Ultra SCSI protocols
and 16-bit arbitration. Each interface is made through two (and only two)
of the connectors J2, J3, and J4 (for Channel A), or J6, J7, and J8 (for
Channel B). Connectors J2 and J6 are 68-pin high density right-angle
receptacles. Connectors J3 and J7 are shielded 68-pin VHDCI 0.8 mm
right-angle receptacles that protrude through the back panel bracket.
Connectors J4 and J8 are 50-pin low density vertical shrouded pin
headers. See Figure 2.1 for the location of these connectors.
Single-ended SCSI active termination is provided on the SYM22801
board. Termination is automatically enabled when only one of the
connectors J2, J3, and J4 (or J6, J7, and J8) is used, or when an 8-bit
device is connected to the 16-bit J3 or J7 connectors. In the latter case,