Product Manual - Disc Drive SCSI-2/SCSI-3 Interface (Vol. 2; Ver. 2), Rev. E
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2.2.13
Reset hold time (25 µs)
The minimum time for which RST is asserted. There is no maximum time.
2.2.14
Selection abort time (200 µs)
The maximum time that a target (or initiator) shall take from its most recent detection of being selected (or
reselected) until asserting a BSY response. This timeout is required to ensure that a target (or initiator) does
not assert BSY after a Selection (or Reselection) phase has been aborted. This is not the selection timeout
period; see Sections 3.1.3.5 and 3.1.4.2 for a complete description.
2.2.15
Selection timeout delay (250 ms recommended)
The minimum time an initiator (or target) should wait for a BSY response during the Selection (or Reselection)
phase before starting the timeout procedure. The drive implements this 250 ms selection timeout delay.
2.2.16
Transfer period (negotiated by Synchronous Data Transfer message)
The minimum time allowed between the leading edges of successive REQ pulses and of successive ACK
pulses while using synchronous data transfers. (See Sections 3.1.5.2 and 3.5.3.2)
2.3
Fast synchronous transfer option
When devices negotiate a synchronous data transfer period of less than 200 ns they are said to be using “fast
synchronous data transfers”. Devices which negotiate a synchronous data transfer period greater than or
equal to 200 ns use timing parameters specified in 2.2. When a fast synchronous data transfer period is
negotiated, those specific times redefined in this section are used; those not redefined remain the same. The
minimum synchronous data transfer period is 100 ns.
2.3.1
Fast Assertion period (30 ns)
This value is the minimum time that a target shall assert REQ while using fast synchronous data transfers.
Also, the minimum time that an initiator shall assert ACK while using fast synchronous data transfers.
2.3.2
Fast cable skew delay (5 ns)
This value is the maximum difference in propagation time allowed between any two SCSI bus signals mea-
sured between any two SCSI devices while using fast synchronous data transfers.
2.3.3
Fast deskew delay (20 ns)
This value is the minimum time required for deskew of certain signals while using fast synchronous data
transfers.
2.3.4
Fast hold time (10 ns)
This value is the minimum time added between the assertion of REQ or ACK and the changing of the data
lines to provide hold time in the initiator or target respectively, while using fast synchronous data transfers.
2.3.5
Fast negation period (30 ns)
This value is the minimum time that a target shall negate REQ while using fast synchronous data transfers.
Also, the minimum time that an initiator shall negate ACK while using fast synchronous data transfers.
