PDP-11/05 (was: PDP-11/05 microcode dump?)

Tony Duell ard.p850ug1 at gmail.com
Tue Jun 15 13:45:02 CDT 2021

On Tue, Jun 15, 2021 at 4:47 PM Tom Uban <tom at figureeightbrewing.com> wrote:
> On 6/15/21 8:58 AM, Tony Duell via cctalk wrote:
> > On Tue, Jun 15, 2021 at 6:34 AM Tom Uban via cctalk
> > <cctalk at classiccmp.org> wrote:
> >
> >> My KM11s are based on Tony Duell's schematic and if you look, switches S3
> >> and S4 are both driving outputs rather than simply switching them to ground,
> >> so I don't think two boards at one time would work if these signals are simply
> >> tied in parallel on slots A2 and B2.
> > I took the switch circuits from the offical KM11 schematics which are
> > either in the PDP11/45 CPU printset or the RK11-C printset that I
> > have, I forget which. I certainly didn't add logic or replace
> > open-collector parts with totem-pole ones.
> >
> > -tony
> I did not mean to imply that you had changed the behavior in your KM11 design.
> You are surely a competent and trusted pdp11 resource :)

I didn't mean to imply anythimg like that either. I was just
confirming that my KM11-a-like and a real one will behave the same
way, so if my version can't be used in pairs in an11/05, then the real
one can't either.. I've been involved with classic computers for long
enough to know that sometimes clones are not exactly identical to the
real thing.

I do have a pair of real KM11s now. Each is a pair of boards that plug
together. The board that goes into the machine's backplane is discrete
transistor lamp drivers, the one that plugs into it (and thus sticks
out of the cardcage) contains the lamps, switches and ICs for the
switch circuitry. I know where they are if you want me to confirm the
IC numbers or whatever.


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