Table 2.4

SCSI Parity Control

 

 

 

 

EPC1

 

ASEP2

Description

 

 

 

 

0

 

0

Does not check for parity errors. Parity is generated when sending

 

 

 

SCSI data. Asserts odd parity when sending SCSI data.

 

 

 

 

0

 

1

Does not check for parity errors. Parity is generated when sending

 

 

 

SCSI data. Asserts even parity when sending SCSI data.

 

 

 

 

1

 

0

Checks for odd parity on SCSI data received. Parity is generated when

 

 

 

sending SCSI data. Asserts odd parity when sending SCSI data.

 

 

 

 

1

 

1

Checks for odd parity on SCSI data received. Parity is generated when

 

 

 

sending SCSI data. Asserts even parity when sending SCSI data.

 

 

 

 

1.EPC = Enable Parity Checking (bit 3 SCSI Control Zero (SCNTL0)).

2.ASEP = Assert SCSI Even Parity (bit 2 SCSI Control One (SCNTL1)).

Table 2.5

SCSI Parity Errors and Interrupts

 

 

 

 

DHP1

 

PAR2

Description

 

 

 

 

0

 

0

Halts when a parity error occurs in the target or initiator mode and does

 

 

 

NOT generate an interrupt.

 

 

 

 

0

 

1

Halts when a parity error occurs in the target mode and generates an

 

 

 

interrupt in the target or initiator mode.

 

 

 

 

1

 

0

Does not halt in target mode when a parity error occurs until the end

 

 

 

of the transfer. An interrupt is not generated.

 

 

 

 

1

 

1

Does not halt in target mode when a parity error occurs until the end

 

 

 

of the transfer. An interrupt is generated.

 

 

 

 

1.DHP = Disable Halt on SATN/ or Parity Error (bit 5 SCSI Control One (SCNTL1)).

2.PAR = Parity Error (bit 0 SCSI Interrupt Enable Zero (SIEN0)).

2-26

Functional Description

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LSI 53C875A technical manual Scsi Parity Control, Scsi Parity Errors and Interrupts