15 Jun
2021
15 Jun
'21
11:49 a.m.
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:
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
On 6/15/21 8:58 AM, Tony Duell via cctalk wrote:
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 On Tue, Jun 15, 2021 at 6:34 AM Tom Uban via
cctalk
<cctalk at classiccmp.org> wrote:
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 :)
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