Avago Technologies LSI53C895A - Manual (Page 142)

4-34 Registers
Table 4.4 shows example transfer periods and rates for fast SCSI-2 and
Ultra SCSI.
MO[4:0] Max SCSI Synchronous Offset [4:0]
These bits describe the maximum SCSI synchronous
offset used by the LSI53C895A when transferring
synchronous SCSI data in either the initiator or target
mode.
Table 4.5 describes the possible combinations and
their relationship to the synchronous data offset used by
the LSI53C895A. These bits determine the
LSI53C895A’s method of transfer for Data-In and
Data-Out phases only; all other information transfers
occur asynchronously.
Table 4.4 Example Transfer Periods and Rates for Fast SCSI-2,
Ultra, and Ultra2
CLK (MHz)
SCSI CLK
÷
SCNTL3
Bits [6:4] XFERP
Synch.
Transfer
Period (ns)
Synch. Transfer
Rate
(Mbytes/s)
160 1 4 25 40
160 2 4 50 20
160 4 4 100 10
80 1 4 50 20
50 1 4 80 12.5
50 1 5 100 10.0
40 1 4 100 10.0
37.50 1 4 106.67 9.375
33.33 1 4 120 8.33
25 1 4 160 6.25
20 1 4 200 5
16.67 1 4 240 4.17