SCSI Registers 4-33
Tabl e 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 LSI53C875A when transferring
synchronous SCSI data in either the initiator or target
mode. Tabl e 4.5 describes the possible combinations an d
their relationship to the synchronous data offset used by
the LSI53C875A. These bits determine the
LSI53C875A’s method of transfer for Data-In and
Data-Out phases only; all other information transfers
occur asynchronously.
Table 4.4 Example Transfer Periodsand Rates for Fast SCSI-2
and Ultra SCSI
CLK (MHz)
SCSI CLK ÷
SCNTL3
Bits [6:4] XFERP
Synch.
Transfer
Period (ns)
Synch. Transfer
Rate
(Mbytes/s)
1601
1. Only with 40 MHz clock.
2450 20
16014 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