On 6/15/21 1:45 PM, Tony Duell wrote: > On Tue, Jun 15, 2021 at 4:47 PM Tom Uban <t...@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@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.
--tom
