MDPE

Master Data Parity Error

6

 

This bit is set when the LSI53C875A as a master detects

 

a data parity error, or a target device signals a parity error

 

during a data phase. This bit is completely disabled by

 

 

the Master Parity Error Enable bit (bit 3 of Chip Test Four

 

(CTEST4)).

 

BF

Bus Fault

5

 

This bit is set when a PCI bus fault condition is detected.

 

A PCI bus fault can only occur when the LSI53C875A is

 

bus master, and is defined as a cycle that ends with a

 

 

Bad Address or Target Abort Condition.

 

ABRT

Aborted

4

 

This bit is set when an abort condition occurs. An abort

 

condition occurs when a software abort command is

 

 

issued by setting bit 7 of the Interrupt Status Zero

 

 

(ISTAT0) register.

 

SSI

Single Step Interrupt

3

 

If the Single Step Mode bit in the DMA Control (DCNTL)

 

register is set, this bit is set and an interrupt is generated

 

after successful execution of each SCRIPTS instruction.

SIR

SCRIPTS Interrupt Instruction Received

2

 

This status bit is set whenever an Interrupt instruction is

 

evaluated as true.

 

R

Reserved

1

IID

Illegal Instruction Detected

0

 

This status bit is set any time an illegal or reserved

 

instruction opcode is detected, whether the LSI53C875A is operating in single step mode or automatically executing SCSI SCRIPTS.

Any of the following conditions during instruction execution also set this bit:

The LSI53C875A is executing a Wait Disconnect instruction and the SCSI REQ line is asserted without a disconnect occurring.

A Block Move instruction is executed with 0x000000 loaded into the DMA Byte Counter (DBC) register, indicating there are zero bytes to move.

4-40Registers

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LSI 53C875A technical manual Mdpe, Abrt, Ssi, Sir, Iid