Best name for PDP-11/05-10

Noel Chiappa jnc at
Thu Feb 25 07:55:11 CST 2016

    > From: Paul Koning

    > FWIW, I have always heard 11/05 and 11/40 respectively.

Good to know that others have the same vibe that I do.

    > From: Bill Degnan

    > putting all of that original 11/10 stuff aside :-)


    > There is a version of the processor handbook with all 4, and there is a
    > version with just 11/40. I have never seen a processor handbook for
    > just the 11/35, 11/05, or 11/10 by itself.

Good point.

BTW, there's often some confusion; some people think the 11/05-10 was the
second PDP-11. It wasn't, it's the fourth, and those processor handbooks
confirm that. The first 11/45 one is dated 1971, the 11/40 one is 1972,
and the one with the four is 1973.

    > I always treated the 11/05 and 11/10 as separate machines, just as much
    > as the 11/05 S and 11/05 NC.

Can you please remind me again what the differences with the 11/05NC are? I
remembered we discussed it, but I'm too lazy to dig through the list archives
for it.

As far as I know, the original 11/05 and original 11/10 differ only in i)
the number on the front, and ii) what options were standard/offered in each;
the hardware is entirely identical.

    > Not sure if there is an 11/10 model S or NC.

There is definitely an 11/10S (again, identical internally, AFAIK, to
the 05S - the DEC manual for the 05S-10S says exactly that).

    > From: Paul Anderson

    > The 11/05 and 11/10 .. use about 6 different backplanes, most of then
    > listed in the Unibus Troubleshooting Guide.

I know of 3, will have to look there to see what else it says.

    > A lot of people have gotten into trouble thinking all the backplanes
    > were the same.

Yes! I know of two for the 11/05-10: one holds one MM11-L, with four SPC
slots; one holds two MM11-L's, with only a single SPC slot. The 11/05S-10S
have a different backplane which holds a single MM11-U, and has 3 SPC slots.

Needless to say, trying to plug an SPC board into a memory slot, etc will
lead to tears (and probably smoke, too... :-)


More information about the cctech mailing list