(SIEN1) register or not. Each bit that is set indicates an occurrence of the corresponding condition.

Reading the SIST1 clears the interrupt condition.

R

Reserved

[7:3]

STO

Selection or Reselection Time-out

2

 

The SCSI device which the LSI53C875A is attempting to

 

select or reselect does not respond within the

 

 

programmed time-out period. See the description of the

 

SCSI Timer Zero (STIME0) register, bits [3:0], for more

 

information on the time-out timer.

 

GEN

General Purpose Timer Expired

1

 

This bit is set when the general purpose timer expires.

 

The time measured is the time between enabling and

 

disabling of the timer. See the description of the SCSI

 

Timer One (STIME1) register, bits [3:0], for more

 

 

information on the general purpose timer.

 

HTH

Handshake-to-Handshake Timer Expired

0

 

This bit is set when the handshake-to-handshake timer

 

expires. The time measured is the SCSI Request to

 

 

Request (target) or Acknowledge-to-Acknowledge

 

 

(initiator) period. See the description of the SCSI Timer

Zero (STIME0) register, bits [7:4], for more information on the handshake-to-handshake timer.

Register: 0x44

SCSI Longitudinal Parity (SLPAR)

Read/Write

7

0

SLPAR

x

x

x

x

x

x

x

x

 

 

 

SLPAR SCSI Longitudinal Parity[7:0]

This register performs a bytewise longitudinal parity check on all SCSI data received or sent through the SCSI core. If one of the bytes received or sent (usually the last) is the set of correct even parity bits, SLPAR should go to zero (assuming it started at zero). As an example, suppose that the following three data bytes and one

SCSI Registers

4-79

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LSI 53C875A technical manual Hth, Handshake-to-Handshake Timer Expired, Scsi Longitudinal Parity Slpar Read/Write