Sun Microsystems Sun Ultra 60 Service Manual page 207

4 Mechanical, electrical, and timing specification definition that support transfer
rates of 20 or 40 Mbytes per second (corresponding to the data path width of an
8-bit, or 16-bit bus, respectively).
4 Peak bandwidth of 40 Mbytes per second (with implemented 16-bit bus width).
The internal SCSI bus is terminated at each end. One set of terminators is located
close to the CD-ROM drive connector on the CD-ROM SCSI card. A second set of
terminators is located close to the 68-pin external SCSI connector. Figure C–10 shows
the SCSI bus configuration.
Figure C–10
C.1.12.1 Host Adapter
The host adapter is a Symbios Logic PCI-SCSI I/O processor IC. The host adapter
and all target devices comply with the Fast-20 single-ended drivers and receivers
characteristics. The electrical characteristics of the output buffers include:
4 Vol (output low) equals 0 to 0.5 Vdc with Iol at 48 mA (signal asserted)
4 Voh (out high) equals 2.5 to 3.7 Vdc (signal negated)
4 trise (rising slew rate) equals 520 mV per nanosecond maximum (0.7 to 2.3 Vdc)
4 tfall (falling slew rate) equals 520 mV per nanosecond maximum (2.3 to 0.7 Vdc)
The Fast-20 electrical characteristics for the host adapter and target device include:
4 Vil (input low) equals 1.0 Vdc maximum (signal true)
4 Vih (input high) equals 1.9 Vdc minimum (signal false)
4 Iil (input low current) equals +/- 20 mA at Vi equals 0.5 Vdc
4 Iih (input high current) equals +/- 20 mA at Vi equals 2.7 Vdc
4 Minimum input hysteresis equals 0.3 Vdc
Configuration for the SCSI Bus
C-27
Functional Description