Synchronous Data Transfer; Synchronous Data Transfer Periods Supported; Req/Ack Offset; Physical Interface - Seagate ST336732LC Product Manual

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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 13 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 13: Synchronous DT DATA transfer periods
Transfer period
M (decimal)
(nanoseconds)
8 6.25
9 12.5
10 25
12 50
25 100
1. This transfer rate is only supported on drives which support the Ultra320 interface
(ST336732 and ST318432 models).
Table 14 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 14: 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 X15 36LP 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 18 and 19 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.
Transfer rate
(megatransfers/second)
1
160.0
80.0
40.0
20.0
10.0
Transfer rate
(megatransfers/second)
1
40.0
20.0
10.0
5.0
Cheetah X15 36LP Product Manual, Rev. D
Transfer rate
(MBytes/sec) on wide bus
1
320.0
160.0
80.0
40.0
20.0