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

[Bill Degnan]

It's no gunkies but I wrote up a few notes about my 11/05 variants and
support issues here:
 https://www.vintagecomputer.net/digital/.

Bill

On Sun, Jun 13, 2021, 4:44 PM Tom Uban via cctalk <cctalk at classiccmp.org>
wrote:

> I am working on the first of my two 11/05s. Interestingly, it has the
> early version M7261E Control
> Logic & Microprogram board and the later version M7260 Data Paths board
> (with circular baud rate
> selector switch) as described in:
>
> http://gunkies.org/wiki/KD11-B_CPU
>
> From the description there, it seems like an older/newer combination, but
> maybe that was common. I
> would not have guessed that the four possible combinations would all work
> together, but maybe they do?
>
> I have a couple different drawing sets for the 11/05 and while some have
> the matching M7260
> schematic, only the GT40 drawings (I found on bitsavers) has the M7261E
> schematic:
>
>
> http://www.bitsavers.org/pdf/dec/graphics/VT11/GT40_Graphic_Terminal_Engineering_Drawings_Feb73.pdf
>
> The GT40 drawings has the PROM listings and related, so I am hoping that
> they match what is in the
> two boards.
>
> Presently, the machine sometimes runs relatively well and other times it
> does not. It does have bit
> 1 stuck ON in memory, but that should be a relatively simple task to
> diagnose as it is not
> intermittent. When the machine is "working" I am able to deposit 0777 at
> 0100 and run. When running
> this simple program, I've experimented with flexing the boards and such,
> so it doesn't seem like an
> obvious poor connection, but that remains to be seen.
>
> The machine is a configuration #2 model (as described in the "gunkies"
> site) and my initial messing
> with KM11 boards, reveals that I can step the microcode with a KM11 in
> either the #1 or #2 position,
> but when two KM11s are installed at the same time, they do not function
> properly together. Is this
> expected or do I have an issue there too?
>
> Thanks much to those who have provided details and documents on the web,
> they have already been of
> great value and will most certainly continue to be a resource in the
> future.
>
> More updates in the future...
>
> --tom
>
> On 5/6/16 5:32 PM, Noel Chiappa wrote:
> >     > From: Mattis Lind
> >
> >     > Thanks Noel for sorting this out.
> >
> > Eh, de nada. But thank you.
> >
> >
> >     >> I wonder if the ucode in the two versions is identical? The uROM
> chip
> >     >> numbers should give it, (if they are the same on both versions,
> albeit
> >     >> in different locations on the board), but I have yet to check.
> Does
> >     >> anyone happen to know?
> >
> > OK, so the situation here is pretty complicated. To start with / make
> things
> > worse, that CPU uses lots of PROMs. Lots and lots and lots and lots of
> PROMs.
> >
> > For the data paths board (M7260), both major versions appear to contain
> the
> > same PROMs (going by the DEC part numbers), but the chip location (Exx)
> > numbers are all different.
> >
> > For the control board (M7261), the C, E ('early' version) and F ('late'
> > version) etch revisions each contain mostly the same PROMs, but
> apparently
> > with slight differences between the sets of PROMs in each (as reflected
> in
> > different DEC part numbers). For details see:
> >
> >   http://gunkies.org/wiki/PDP-11/05#Control_PROMs
> >
> > to which I have just added all the gory details.
> >
> > As to getting the contents of all of them dumped in machine-readable
> form -
> > oi vey!
> >
> >
> >     >> on the earlier version (prints for that version are in the GT40
> prints
> >     >> online
> >
> > It turns out that I have hard-copy prints for the "C" etch revision of
> the
> > M7261, which do not yet appear to be online; the GT40 prints have the "E"
> > etch revision.
> >
> > I will scan the pages for that revision of the board, and put them up
> 'soon'.
> > (I'm not doing the whole print set, it's about 1" thick, and most of
> them are
> > for other things anyway, like MM11-L memory, etc.)
> >
> >       Noel
> >
>
>