1.3.1 The PCI Interface
PCI, a high-speed standard local bus, interfaces I/O components to the processor and memory subsystems in equipment ranging from PCs to servers. The PCI functionality for the SYM8953U is contained within the Symbios SYM53C895A PCI to Ultra2 Controller with LVD Link Universal Transceivers. The SYM53C895A connects directly to the PCI bus and generates signal timing and bus protocol in compliance with the PCI Specification Revision 2.2.
The PCI interface operates as a 32-bit DMA bus master capable of
64-bit addressing. The connection is made through edge connector J1, shown in Figure 2.1. The signal definitions and pin numbers conform to the PCI Local Bus Specification Revision 2.2 standard. The SYM8953U host adapter 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 SYM8953U is contained within the SYM53C895A. This chip is a PCI to Ultra2 SCSI Controller with LVD Link Universal Transceivers. It connects directly to the SCSI bus and generates signal timing and bus protocol in compliance with SCSI standards.
The SCSI interface on the SYM8953U operates as an 8-bit or 16-bit interface. It supports 8-bit or 16-bit, synchronous and asynchronous, LVD or SE, Fast, Ultra and Ultra2 SCSI protocols in various combinations. The interface is made through connectors J2 and J3 (see Figure 2.1). Internal connector J2 is a 68-pin HD right angle latching connector. External connector J3 is a shielded 68-pin HD right angle connector exposed in the back panel bracket. An on-board LED (labeled Activity) indicates SCSI bus activity. LVD/SE dual mode, active termination is provided on the SYM8953U board. Termination is automatically disabled when both SCSI connectors are used. The SYM8953U supplies SCSI bus TERMPWR through a blocking diode and a self-resetting 1.5 A short circuit protection device. A 40 MHz oscillator is installed on the SYM8953U to provide the clock frequency to the SYM53C895A that is necessary to support Ultra2 SCSI transfers of up to 80 Mbytes/s.
1-4 | Using the SYM8953U Host Adapter |
