target. In target mode, this bit is set when the SATN/ signal is asserted by the initiator.

CMP

Function Complete

6

 

This bit is set when an arbitration only or full arbitration

 

sequence is completed.

 

SEL

Selected

5

 

This bit is set when the LSI53C875A is selected by

 

 

another SCSI device. The Enable Response to Selection

 

bit must be set in the SCSI Chip ID (SCID) register (and

 

the Response ID Zero (RESPID0) and Response ID One

 

(RESPID1) register must hold the chip’s ID) for the

 

 

LSI53C875A to respond to selection attempts.

 

RSL

Reselected

4

 

This bit is set when the LSI53C875A is reselected by

 

 

another SCSI device. The Enable Response to

 

 

Reselection bit must be set in the SCID register (and the

 

Response ID Zero (RESPID0) and Response ID One

 

 

(RESPID1) registers must hold the chip’s ID) for the

 

 

LSI53C875A to respond to reselection attempts.

 

SGE

SCSI Gross Error

3

 

This bit is set when the LSI53C875A encounters a SCSI

 

Gross Error Condition. The following conditions can result

 

in a SCSI Gross Error Condition:

 

Data Underflow – reading the SCSI FIFO when no data is present.

Data Overflow – writing too many bytes to the SCSI FIFO, or the synchronous offset causes overwriting the SCSI FIFO.

Offset Underflow – the LSI53C875A is operating in target mode and a SACK/ pulse is received when the outstanding offset is zero.

Offset Overflow – the other SCSI device sends a SREQ/ or SACK/ pulse with data which exceeds the maximum synchronous offset defined by the SCSI Transfer (SXFER) register.

A phase change occurs with an outstanding synchronous offset when the LSI53C875A is operating as an initiator.

SCSI Registers

4-77

Page 169
Image 169
LSI 53C875A technical manual This bit is set when an arbitration only or full arbitration