Examples Of Synchronous Transfer Periods And Rates For Scsi-1 - LSI LSI53C875A Technical Manual

4-32
(This SCSI synchronous core clock is determined in
SCNTL3 bits [6:4], ExtCC = 1 if SCNTL1 bit 7 is asserted
and the LSI53C875A is sending data. ExtCC = 0 if the
LSI53C875A is receiving data.)
SXFERP = 100
Where:
SXFERP
SSCP
SSCF
ExtCC
Table 4.3 shows examples of synchronous transfer periods and rates for
SCSI-1.
Table 4.3 Examples of Synchronous Transfer Periods and Rates
for SCSI-1
SCSI CLK
SCNTL3
CLK (MHz) Bits [6:4]
66.67 3
66.67 3
50 2
50 2
40 2
37.50 1.5
33.33 1.5
25 1
20 1
16.67 1
Registers
25 = 4
Synchronous transfer period.
SCSI synchronous core period.
SCSI synchronous core frequency.
Extra clock cycle of data setup.
XFERP
(SXFER Transfer
Bits [7:5]) Period (ns)
4
5
4
5
4
4
4
4
4
4
Synch. Synch.
Transfer Rate
(Mbytes/s)
180 5.55
225 4.44
160 6.25
200 5
200 5
160 6.25
180 5.55
160 6.25
200 5
240 4.17