strange number corruption on pdp11/34

Noel Chiappa jnc at
Tue Jan 27 20:03:15 CST 2015

    > 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

    > 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).


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