IBM IC35L036UWDY10 Hard Drive Specifications - Page 200

REQ/ACK Offset, Transfer Wide Exponent, PCOMP_EN, RD_STRM, WR_FLOW, The REQ/ACK

Page 200 highlights

If DT_REQ is set to one and IU_REQ is set to zero, the following values are used. Initiator Request Target Response Target Transfer Period (ns) Transfer Rate 0

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If DT_REQ is set to one and IU_REQ is set to zero, the following values are used.
Asynch
(Asynch Mode)
Mt = 19h
26 <= Mi <= 255
Fast-10
100
Mt = 19h
13 <= Mi <= 25
Fast-20
50
Mt = 0Ch
11 <= Mi <= 12
Fast-40
25
Mt = 0Ah
10 <= Mi <= 10
Fast-80
12.5
Mt = 09h
0 <= Mi <=
9
Transfer Rate
Target Transfer
Period (ns)
Target
Response
Initiator Request
Figure 188. Initiator Request/Target Response (DT_REQ = 1, IU_REQ = 0
If both DT_REQ and IU_REQ are set to zero, the following values are used.
Asynch
(Asynch Mode)
Mt = 32h
51 <= Mi <= 255
Fast-5
200
Mt = 32h
26 <= Mi <= 50
Fast-10
100
Mt = 19h
13 <= Mi <= 25
Fast-20
50
Mt = 0Ch
11 <= Mi <= 12
Fast-40
25
Mt = 0Ah
0 <= Mi <= 10
Transfer Rate
Target Transfer
Period (ns)
Target
Response
Initiator Request
Figure 189. Initiator Request/Target Response (DT_REQ = 0, IU_REQ = 0
!
REQ/ACK Offset
determines the maximum number of REQs allowed to be outstanding before a
corresponding ACK is received at the drive during synchronous or paced transfers.
The REQ/ACK
Offset value is chosen to prevent overflow conditions in the reception buffer and offset counter of the
drive. The drive supports maximum offset of 127 (7Fh). A REQ/ACK Offset value of zero indicates
asynchronous data transfer mode and that the Transfer Period Factor and the protocol options bits
except QAS_REQ will be ignored.
!
Transfer Wide Exponent
defines the transfer width to be used during DATA IN and DATA OUT
phases. If any of the protocol options bits other than QAS_REQ are set to one, then only wide transfer
agreements are valid. The following values are supported.
00h: 8 bit data bus (Narrow transfer agreement).
01h: 16 bit data bus (Wide transfer agreement).
!
PCOMP_EN
(Precompensation Enable) is used to negotiate if the precompensation is enabled on all
signals transmitted during DT DATA phases. The drive supports PCOMP_EN.
!
RTI
(Retain Training Information) is used to negotiate if the saving of paced data transfer training in-
formation is made so that the retraining is not necessary on each connection. The drive support RTI.
!
RD_STRM
(Read Streaming and Read Flow Control Enable) is used to negotiate if read streaming
and read flow control are enabled. The drive supports RD_STRM.
!
WR_FLOW
(Write Flow Control Enable) is used to negotiate if write flow control is enabled during
write streaming. The drive supports WR_FLOW.
Ultrastar 146Z10 hard disk drive specifications
184