AIP

Arbitration in Progress

4

 

Arbitration in Progress (AIP = 1) indicates that the

 

 

LSI53C875A has detected a Bus Free condition, asserted

 

SBSY, and asserted its SCSI ID onto the SCSI bus.

 

LOA

Lost Arbitration

3

 

When set, LOA indicates that the LSI53C875A has

 

 

detected a bus free condition, arbitrated for the SCSI bus,

 

and lost arbitration due to another SCSI device asserting

 

the SSEL/ signal.

 

WOA

Won Arbitration

2

 

When set, WOA indicates that the LSI53C875A has

 

 

detected a Bus Free condition, arbitrated for the SCSI

 

 

bus and won arbitration. The arbitration mode selected in

 

the SCSI Control Zero (SCNTL0) register must be full

 

 

arbitration and selection to set this bit.

 

RST

SCSI RST/ Signal

1

 

This bit reports the current status of the SCSI RST/

 

 

signal, and the SRST signal (bit 6) in the Interrupt Status

 

Zero (ISTAT0) register. This bit is not latched and may

 

 

change as it is read.

 

SDP0SCSI SDP0/ Parity Signal0

This bit represents the active HIGH current status of the SCSI SDP0/ parity signal. This signal is not latched and may change as it is read.

Register: 0x0E

SCSI Status One (SSTAT1)

Read Only

7

 

 

 

4

3

2

1

0

 

 

FF[3:0]

 

SDP0L

MSG

C_D

I_O

 

 

 

 

 

 

 

 

 

0

0

 

0

0

x

x

x

x

 

 

 

 

 

 

 

 

 

FF[3:0]

 

FIFO Flags

 

 

 

 

[7:4]

These four bits, along with SCSI Status Two (SSTAT2) bit 4, define the number of bytes or words that currently reside in the LSI53C875A’s SCSI synchronous data FIFO as shown in Table 4.6. These bits are not latched and they will change as data moves through the FIFO. The SCSI FIFO can hold up to 31 bytes for narrow SCSI

SCSI Registers

4-43

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Image 135
LSI 53C875A technical manual Aip, Loa, Woa