LSI U80ALVD - Manual (Page 16)

1-4 Using the LSIU80ALVD
1.3.2 The SCSI Interface
The SCSI functionality for the LSIU80ALVD is contained within the
LSI53C895A. The LSI53C895A connects directly to the SCSI bus and
generates signal timing and bus protocol in compliance with the SCSI
standard.
The SCSI interface on the LSIU80ALVD 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 that
protrudes through the back panel bracket.
An on-board LED (labeled Activity) indicates SCSI bus activity.
LVD/SE dual mode, active termination is provided on the LSIU80ALVD.
Termination is automatically disabled when both SCSI connectors are
used.
The LSIU80ALVD 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 LSIU80ALVD to provide the clock
frequency to the LSI53C895A that is necessary to support Ultra2 SCSI
transfers of up to 80 Mbytes/s.