PDP-11/70 progress (and a cry for help)

Fritz Mueller fritzm at fritzm.org
Tue Feb 16 19:08:27 CST 2021

> On Tue, Feb 16, 2021 at 2:36 AM Fritz Mueller via cctalk <cctalk at classiccmp.org> wrote:
> So you could set up on t4 or t5 of that microinstruction with the KM11...

> On Feb 16, 2021, at 11:08 AM, Josh Dersch <derschjo at gmail.com> wrote:
> I can't, though -- all of this stuff works fine when running slowly :)

Oh right -- I keep forgetting that part!  So that really does leave you with just the LA to catch things in the act I guess.

> Right now I'm thinking it is most likely the AMX selecting the wrong input (I'm guessing that BMX is correctly selecting KOMX, to get the constant "2" for the add operation).

I agree; seems a good place to look next.

> Have the 11/70 microcode PROMs been dumped?  I had to recreate the 11/05 PROM from the listings in the engineering drawings...

I am not sure?  For the 11/45, I also keyed it in by hand from the engineering drawings, but since it is only a 32x8 bit ROM this was pretty easy.


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