strange number corruption on pdp11/34

Johnny Billquist bqt at
Thu Jan 29 18:15:24 CST 2015

On 2015-01-29 20:14, Pete Turnbull wrote:
> On 29/01/2015 18:32, Jacob Ritorto wrote:
>> Johnny, you're insisting that I put in the real numbers for address
>> and csr
>> for testing the drive (for instance).  I'm going to do that next, here.
>> But are you understanding that some of us think that the reason it
>> prompts
>> a zero default is that it's a manifestation of the zero bug and that the
>> real value *is* actually safe but hidden in memory?  Did you see the
>> RSX-11M crash dump I posted in the other thread?
> I didn't see a crash dump, but did you see what I posted yesterday?

I haven't seen any crash dumps either.

> The default in XXDP for CSRs is very often zero, and I'm pretty sure it
> is so in the RL02 diagnostics (I've ont checked the listing for that
> particular one, but I did look at some others that were more readily to
> hand).  So when it asked you for input and you just hit "return", you
> really did tell it zero.  Applying the principle of Occam's Razor, and
> assuming the simplest solution is the correct one, you got a lot of
> zeros back because it was accessing memory instead of the controller you
> wanted.
> It's hard to believe you have a CPU fault that consistently prints
> numbers as zeros yet happily boots three different OSs.  Still, I'll
> change the tune if you re-run XXDP with sensible inputs.

Totally agree with that one.


Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol

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