Synchronous Data Transfer; Synchronous Data Transfer Periods Supported; Req/Ack Offset; Physical Interface - Seagate ST318404LW Product Manual

Cheetah 18XL Product Manual, Rev. A
9.5

Synchronous data transfer

9.5.1

Synchronous data transfer periods supported

Table 11 and Section 9.5.2 list Synchronous Data transfer periods supported by the drive. 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.
Table 11: Synchronous 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

The maximum value supported by the Cheetah 18XL family drives for REQ/ACK offset is 63 (3Fh).
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 19 and 20 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, part number
75789509.
9.6.1

DC cable and connector

ST318404LW drives receive DC power through a 4 pin connector (see Figure 21 for pin assignment) mounted
at the rear of the main PCBA. Recommended part numbers of the mating connector are listed below, but equiv-
alent 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 15 and 16.
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)
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