Programming Model

Programming the SCSI Error Status and Interrupt Registers

This section provides address and bit level description of the SCSI

interrupt control register and status register.

3

SCSI Error Status Register

ADR/SIZ

 

 

 

 

$FFF4202C (8 bits)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BIT

31

30

 

29

 

28

27

 

26

25

24

 

 

 

 

 

 

 

 

 

 

 

 

NAME

 

 

 

 

 

 

PRTY

 

EXT

LTO

SCLR

 

 

 

 

 

 

 

 

 

 

 

 

OPER

R

R

 

R

 

R

R

 

R

R

W/R-0

 

 

 

 

 

 

 

 

 

 

 

 

RESET

0

0

 

0

 

0

0 PL

 

0 PL

0 PL

0

 

 

 

 

 

 

 

 

 

 

 

SCLR

 

Writing a 1 to this bit clears bits 25 through 27 (LTO,

 

 

 

EXT, and PRTY). Reading this bit always yields 0.

LTO,EXT,PRTY These bits indicate the status of the last Local Bus error condition encountered by the SCSI processor while performing DMA accesses to the Local Bus.

A Local Bus error condition is flagged by the assertion of

TEA*.

When the SCSI processor receives TEA*:

If the source of the error is local time-out, then LTO is set and EXT and PRTY are cleared.

If the source of the TEA* is due to an error in going to the VMEbus, then EXT is set and the other two status bits are cleared.

If the source of the error is DRAM parity check error, then PRTY is set and the other two status bits are cleared.

If the source of the error is none of the above conditions, then all three bits are cleared.

Writing a 1 to bit 24 (SCLR) also clears all three bits.

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Motorola MVME1X7P manual Programming the Scsi Error Status and Interrupt Registers, Scsi Error Status Register