Table 4.6 SCSI Synchronous Data FIFO Word Count (Cont.)

 

 

 

 

 

Bytes or Words

FF4

 

 

 

 

in the

(SSTAT2 bit 4)

FF3

FF2

FF1

FF0

SCSI FIFO

 

 

 

 

 

 

1

0

0

1

1

19

 

 

 

 

 

 

1

0

1

0

0

20

 

 

 

 

 

 

1

0

1

0

1

21

 

 

 

 

 

 

1

0

1

1

0

22

 

 

 

 

 

 

1

0

1

1

1

23

 

 

 

 

 

 

1

1

0

0

0

24

 

 

 

 

 

 

1

1

0

0

1

25

 

 

 

 

 

 

1

1

0

1

0

26

 

 

 

 

 

 

1

1

0

1

1

27

 

 

 

 

 

 

1

1

1

0

0

28

 

 

 

 

 

 

1

1

1

0

1

29

 

 

 

 

 

 

1

1

1

1

0

30

 

 

 

 

 

 

1

1

1

1

1

31

 

 

 

 

 

 

SDP0L

Latched SCSI Parity

3

 

This bit reflects the SCSI parity signal (SDP0/),

 

 

corresponding to the data latched in the SCSI Input Data

 

Latch (SIDL). It changes when a new byte is latched into

 

the least significant byte of the SIDL register. This bit is

 

active HIGH, in other words, it is set when the parity

 

 

signal is active.

 

MSG

SCSI MSG/ Signal

2

C_D

SCSI C_D/ Signal

1

I_O

SCSI I_O/ Signal

0

 

These three SCSI phase status bits (MSG, C_D, and

 

 

I_O) are latched on the asserting edge of SREQ/ when

 

operating in either the initiator or target mode. These bits

 

are set when the corresponding signal is active. They are

 

useful when operating in the low level mode.

 

SCSI Registers

4-45

Page 137
Image 137
LSI 53C875A technical manual SDP0L, Msg