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

Tom Uban tom at figureeightbrewing.com
Tue Jun 15 13:49:34 CDT 2021

On 6/15/21 1:45 PM, Tony Duell wrote:
> 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.
> -tony
Thank you for your offer, but I have one original KM11 (set) as well,
but it is not functional. I think the transistors on the extender half have
been mashed to many times and it is low in my priority list to fix as I
have to of my own "reproduction" boards.


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