Scsi - Sun Microsystems Ultra 60 Service Manual

C.1.14

SCSI

The system unit implements a small computer system interface (SCSI) Fast-20
(UltraSCSI) parallel interface bus. The UltraSCSI provides the following:
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.
the SCSI bus configuration.
FIGURE C-10
C.1.14.1 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:
C-30 Sun Ultra 60 Service Manual • August 2001
Efficient peer-to-peer I/O bus devices.
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).
Peak bandwidth of 40 Mbytes per second (with implemented 16-bit bus width).
CD-ROM
Disk 1
drive
(UltraSCSI)
(8-bit)
T
SCSI bus
Configuration for the SCSI Bus
V (output low) equals 0 to 0.5 Vdc with Iol at 48 mA (signal asserted)
ol
V (out high) equals 2.5 to 3.7 Vdc (signal negated)
oh
t (rising slew rate) equals 520 mV per nanosecond maximum
rise
(0.7 to 2.3 Vdc)
t (falling slew rate) equals 520 mV per nanosecond maximum
fall
(2.3 to 0.7 Vdc)
Host
Disk 0
adapter
(UltraSCSI)
(UltraSCSI)
T
Internal SCSI bus
FIGURE C-10
External
devices
(UltraSCSI)
T
SCSI bus
External to chassis
shows