LSI SYM22801 - Manual (Page 14)

1-4 Using the SYM22801 Host Adapter
only the upper 8 data bits are automatically terminated. The SYM22801
supplies SCSI bus TERMPWR (termination power) through a blocking
diode and a self-resetting 1.5 A short circuit protection device. The
onboard LED lights when TERMPWR is shorted. Separate switches for
each channel allow user override of termination.
A 40 MHz oscillator is installed on the SYM22801 to provide the clock
frequency to the SYM53C876 that is necessary to support Wide Ultra
SCSI transfers of up to 40 Mbytes/s.
1.3.3 Ultra SCSI
The SYM22801 has full support for Ultra SCSI as well as supporting Fast
SCSI simultaneously. Ultra SCSI is an extension of the SCSI-3 family of
standards that expands the bandwidth of the SCSI bus, allowing faster
synchronous data transfers. Special SCSI cables are specified for
operation with Ultra SCSI devices, and you must consider the total
number of devices and the length of the SCSI bus when setting up your
system. See Chapter 2, Installing the SYM22801 Host Adapter for a
detailed explanation of SCSI bus connections.