Example Transfer Periods And Rates For Fast Scsi-2; And Ultra Scsi - LSI LSI53C875A Technical Manual

Table 4.4 shows example transfer periods and rates for fast SCSI-2 and
Ultra SCSI.
Table 4.4

Example Transfer Periods and Rates for Fast SCSI-2

and Ultra SCSI

SCSI CLK
SCNTL3
CLK (MHz) Bits [6:4]
1
160 2
1
160 4
80 1
50 1
50 1
40 1
37.50 1
33.33 1
25 1
20 1
16.67 1
1. Only with 40 MHz clock.
MO[4:0] Max SCSI Synchronous Offset
These bits describe the maximum SCSI synchronous
offset used by the LSI53C875A when transferring
synchronous SCSI data in either the initiator or target
mode.
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.
SCSI Registers
Synch.
Transfer
XFERP Period (ns)
4
4
4
4
5
4
4
4
4
4
4
Table 4.5 describes the possible combinations and
Synch. Transfer
Rate
(Mbytes/s)
50
100
50
80 12.5
100 10.0
100 10.0
106.67 9.375
120 8.33
160 6.25
200
240 4.17
20
10
20
5
[4:0]
4-33