Motorola MVME1X7P User Manual

Page of 316
Programming Model
http://www.motorola.com/computer/literature
4-19
4
cleared during normal system operation. DERC also 
allows the write portion of a read-modify-write to 
complete regardless of whether or not there was a multiple 
bit error during the read portion of the read-modify-write. 
DERC also affects scrub cycles.
Scrub Control Register
RWB0
RWB0 is a general-purpose read/write bit.
SBEIEN
Setting SBEIEN causes the logging of a single-bit error to 
create a true pulse on the INT signal pin. 
SCRBEN This control bit enables the scrubber to operate. When 
SCRBEN is set, the MCECC sector immediately 
performs a scrub of the entire DRAM array. When the 
scrub is complete, if software has cleared SCRBEN, then 
scrubbing is not done again, until software sets the 
SCRBEN bit. If software has not cleared the SCRBEN bit, 
then when the amount of time indicated in the Scrub 
Period (SBPD) register expires, the MCECC sector scrubs 
the DRAM array again. It continues to perform scrubs of 
the entire DRAM array at the frequency indicated in the 
SBPD register. The scrubber does not start a new scrub 
once the SCRBEN bit is cleared. The time between scrubs 
is approximately two seconds times the value stored in the 
SBPD register. Note that a power-up, local, or software 
reset stops the scrubber. 
ADR/SIZ
1st $FFF43024/2nd $FFF43124 (8-bits)
BIT
31
30
29
28
27
26
25
24
NAME
0
0
0
SCRB SCRBEN 0
SBEIEN
RWB0
OPER
R
R
R
R
R/W
R
R/W
R/W
RESET
0 PLS
0 PLS
0 PLS
0 PLS 0 PLS
X
0 PLS
0 PLS