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Status Register
BIT 13
PARITY ERROR (PE)
PE indicates a parity error from memory is
detect~~d
while
the
controller
is
performing
a
Write
or Writ.e-Check
command.
Diagnostics
DECXll
Drive
Not a Drive Problem
RH7e
M8T52
M81Sl
6.2.7
Status Register
BIT 14
WRITE CHECK ERROR (WCE)
- RH70
BIT "9
&
1"
- RH780
weE sets when the controller is performing a write check
operation
and
a
word
on
the
disk
does
not
match
the
corresponding word in memory.
The thing to be aware of on troubleshooting WCE' s is the
s tat us
0
f the d a t a c h e c k err
0
r bit.
If Da taCh e c k i s s e t
with
weE
set,
the
word
on
the
Disk
itself
was
read
inc
0
r r e c t 1 Y • In
0
the 'r wo r d s, ig nor e th e WC E •
If weE is set alone one of two things happen.
Data was
changed on the parallel transfer to the RM Adapter or the
Data was changed from the RM Adapter to memory.
Areas that could cause WCE.
1.
MASSBUS - if an even number of bi ts were effected since
parity would not detect this problem.
2.
Data Transce iver in RH.
3.
Incorrect Data Patterns on Pack when running Performance
Exerciser.
4.
NPR timing is bad. - 11/70
36
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