R

Reserved

[7:3]

STO

Selection or Reselection Time-out

2

 

When the SCSI device which the LSI53C810A 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 (0xC4)

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, SCSI Longitudinal Parity (SLPAR) should go to zero (assuming it started at zero). As an example, suppose that the following three data bytes and one check byte are received from the SCSI bus (all signals are shown active HIGH):

5-54

Operating Registers

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LSI 53C810A Register 0x44 0xC4, Handshake-to-Handshake Timer Expired, Scsi Longitudinal Parity Slpar Read/Write