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64 Barracuda 180 Product Manual, Rev. A
Notes.
[1] See the SCSI Interface Product Manual.
[2] Maximum SCSI asynchronous interface transfer rate is given in Section 4.2.3 of this manual.
[3] Synchronous Transfer Period is determined by negotiations between an Initiator and a Drive. The Drive is
capable of setting periods as given in Section 9.5. See also the SCSI Interface Product Manual for a
description of synchronous data transfer operation.
9.11 Drive activity LED
The following table provides drive activity LED status.
Data In Byte Transfer (parameter) T24 4.5-12 0.04
µ
s
Data Out Byte Transfer (parameter) T25 4.5-13 0.04
µ
s
Next Data In Byte Access (parameter) T26 4.5-12 0.12
µ
s
Next Data Out Byte Access (parameter) T27 4.5-13 0.12
µ
s
Data In Byte Transfer (media) [2] T28 4.5-12 0.04
µ
s
Data Out Byte Transfer (media) [2] T29 4.5-13 0.04
µ
s
Next Data In Byte access (media [2] T30 4.5-12 0.12
µ
s
Next Data Out Byte access (media [2] T31 4.5-13 0.12
µ
s
MSG IN Byte Transfer T32 4.5-5,7,8,14,15 0.04
µ
s
MSG OUT Byte Transfer T33 4.5-2 0.04
µ
s
STATUS Byte Transfer T34 4.5-5,8,15 0.04
µ
s
Synchronous Data Transfer Characteristics:
Request Signal Transfer Period [3] –– various (800 ns max)
Table 18: Drive activity LED status
Spindle status Command status LED status
Spinning up with DC power applied N/A On until spinup is complete
Spun down Start Unit On while processing the command
Powered down by removal of DC power N/A Off due to absence of power
Spun up Stop Unit On while processing the command
Spun down No command activity Off
Spun down Write/Read Buffer On while processing the command
Spun down SCSI Bus Reset On while processing the reset
Spun down Test Unit Ready On while processing the command
Spun up No command activity Off
Spun up Write/Read On while processing the command
Spun up SCSI Bus Reset On while processing the reset
Spun up Test Unit Ready On while processing the command
Spun up Format with Immediate option on On while the command is initially processed
Spun up Format without Immediate LED toggles on/off on each cylinder boundary
Table 17: Disc drive SCSI timing (Continued)
Description
Waveform
symbol [1]
Waveform
table [1] Typical timing