Motorola MVME1X7P - Manual (Page 235)

Programming Model
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3
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.
SCSI Error Status Register
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.
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