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Cheetah 15K.3 SCSI Product Manual, Rev. G
9.5
Synchronous data transfer
9.5.1
Synchronous data transfer periods supported
The data transfer period to be used by the drive and the initiator is established by an exchange of messages
during the Message Phase of operation. See the section on message protocol in the SCSI Interface Product
Manual, part number 75789509. In the following tables, M is the synchronous period value (in the transfer rate
negotiation message) that represents the associated transfer period and transfer rate values.
Table 12 lists the synchronous data transfer periods supported by the drive in DT DATA phase. DT DATA phase
is only allowed when using the LVD interface.
Table 12:
Synchronous DT DATA transfer periods
Transfer period
M (decimal)
(nanoseconds)
8
6.25
9
12.5
10
25
12
50
25
100
Table 13 lists the synchronous data transfer periods supported by the drive in ST DATA phase. ST DATA phase
is allowed with either LVD or SE interface except as noted.
Table 13:
Synchronous ST DATA transfer periods
Transfer period
M (decimal)
(nanoseconds)
10
25
12
50
25
100
50
200
1.
This transfer rate is only allowed when using the LVD interface.
9.5.2
REQ/ACK offset
Cheetah 15K.3 SCSI family drives support REQ/ACK offset values from 7 to 63 (3Fh). Offsets of 1 through 6
are negotiated to 0 (asynchronous transfer).
9.6
Physical interface
This section describes the connectors, cables, signals, terminators and bus timing of the DC and SCSI I/O
interface. See Section 9.8 and Section 9.9 for additional terminator information.
Figures 22 and 23 show the locations of the DC power connector, SCSI interface connector, drive select head-
ers, and option select headers.
Details of the physical, electrical and logical characteristics are given in sections following, while the SCSI
operational aspects of Seagate drive interfaces are given in the SCSI Interface Product Manual .
9.6.1
DC cable and connector
ST373453LW and ST336753LW drives receive DC power through a 4-pin connector (see Figure 24 for pin
assignment) mounted at the rear of the main PCBA. Recommended part numbers of the mating connector are
listed below, but equivalent parts may be used.
Type of cable
Connector
14 AWG
MP 1-480424-0
LC model drives receive power through the 80-pin I/O connector. See Tables 17 and 18.
Transfer rate
(megatransfers/second)
160.0
80.0
40.0
20.0
10.0
Transfer rate
(megatransfers/second)
1
40.0
20.0
10.0
5.0
Contacts (20-14 AWG)
AMP 60619-4 (Loose Piece)
AMP 61117-4 (Strip)
Transfer rate
(MBytes/second) on wide bus
320.0
160.0
80.0
40.0
20.0
55
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