Avago Technologies LSI8751D User Manual
Page 132
5-16
SCSI Operating Registers
The LSI53C875 is connected to a hard disk which can
transfer data at 10 Mbytes/s synchronously. The
LSI53C875’s SCLK is running at 40 MHz. The
synchronous transfer period (SXFERP) is found as
follows:
Synchronous Send Rate = (SCLK/SCF)/XFERP
Synchronous Receive Rate = (SCKL/SCF)/4.
Where:
SCLK
SCSI clock.
SCF
SCSI synchronous core frequency.
Table 5.2
Examples of Synchronous Transfer Periods for SCSI-1 Transfer Rates
CLK
(MHz)
SCSI CLK
÷
SCNTL3
Bits [6:4]
XFERP
(SXFER)
Bits [7:5]
Synch. Send
Rate
(Mbytes/s)
Synch.
Transfer
Period (ns)
Synch. Receive
Rate (Mbytes)
Synch.
Receive
Period (ns)
80
4
4
5
200
5
200
80
4
5
4
250
5
200
66.67
3
4
5.55
180
5.55
180
66.67
3
5
4.44
225
5.55
180
50
2
4
6.25
160
6.25
160
50
2
5
5
200
6.25
160
40
2
4
5
200
5
200
37.50
1.5
4
6.25
160
6.25
160
33.33
1.5
4
5.55
180
5.55
180
25
1
4
6.25
160
6.25
160
20
1
4
5
200
5
200
16.67
1
4
4.17
240
4.17
240