strange number corruption on pdp11/34

Jacob Ritorto jacob.ritorto at
Tue Jan 27 20:20:54 CST 2015

Awesome, I'm just going to swap cpu boards and try again, then.  Never
hurts to have floating point, I guess (actually, in the pdp11 world, I bet
there are cases where it hurts :\ )

Thanks Noel!

On Tue, Jan 27, 2015 at 9:03 PM, Noel Chiappa <jnc at>

>     > From: Johnny Billquist
>     > Is noone paying attention to the fact (and my previous comment) about
>     > using 0 for CSR and vector???
> Err, no. :-)
> But seriously, I'm a bit boggled that a diagnostic program would _not_ have
> as default the 'standard' vector/address. So I'm kind of assuming that the
> 0's are somehow bug results.
>     > From: Jacob Ritorto
>     > I grabbed a set of pdp11/34a boards ... Can I plug them straight into
>     > this blackplane that's currently housing my misbehaving 11/34?
> Yes, if the backplane is some flavour of DD11-P (I don't know of any
> backplane that supports the 11/34 but not the 11/34A, but I only have
> direct
> confirmatory documentation on the DD11-P, and it supports both).
> My vague recollection is that one can use _either_ the M7265/M7266 (but as
> paired set) _or_ the M8265/M8266 set, but you can't mix and match them. But
> don't depend on that (I'm too tired to dig into this tonight, I'll do so
> tomorrow).
>     > Backplane markings are very faded but seem to say dd11-pk.
> Yeah, that's the 11/34 backplane (actually, the DD11-P part - the -PK is
> the
> version with the wire harness to work in a BA11-L or BA11-K; the -PF is for
> the BA11-F or BA11-P).
>         Noel

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