Motorola MVME1X7P User Manual

Programming Model

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3-27

SCC Error Status and Interrupt Control Registers

This section provides addresses and bit level descriptions of the SCC
interrupt control registers and status registers.

SCC Error Status Register

SCLR

Writing a 1 to this bit clears bits 25 through 28 (LTO,
EXT, PRTY, and RTRY). Reading this bit always yields
0.

LTO,EXT,

These bits indicate the status of the last Local Bus

PRTY,RTRY error condition encountered by the SCC while performing

DMA accesses to the Local Bus. A Local Bus error
condition is flagged by the assertion of TEA*. When the
SCC receives TEA* if the source of the error is local-
time-out, then LTO is set and EXT, PRTY, and RTRY 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 three
status bits are cleared. If the source of the error is DRAM
parity check error, then PRTY is set and the other three
status bits are cleared. If the source of the TEA* is
because a retry was needed, then RTRY is set and the
other three status bits are cleared. If the source of the error
is none of the above conditions, then all four bits are
cleared. Writing a 1 to bit 24 (SCLR) also clears all four
bits.

ADR/SIZ

$FFF4201C (8 bits)

BIT

NAME

RTRY

PRTY

EXT

LTO

SCLR

OPER

W/R-0

RESET

0 PL