Next project: 11/24. Does it need memory?

Ethan Dicks ethan.dicks at
Fri Oct 16 12:35:28 CDT 2020

On Thu, Oct 15, 2020 at 10:52 PM Chris Zach via cctalk
<cctalk at> wrote:
> Next up is the 11/24,
> this is one of the 5.25 inch rack mounts with a CPU, KT24, and no memory.
> First question: Will ODT respond at all with no memory on the Unibus?

I don't recall.  I think so but it's possible it won't.  ODT works
from my 11/34 with bad RAM, but I've never tried any machine with no
RAM.  It doesn't help that different models have different
implementations of ODT.

> Second question: Can a 128kw memory board from an 11/34 work in an
> 11/24? Or do I need one of the 11/44 boards to make it go?

AFAIK, you should be able to use that 128kw memory board just fine,
but I don't recall if they play nice with the KT24 in going over
18-bits.  I have a couple of 1MB boards in my 11/24 (they were not
cheap in the 80s) which I got after I got a KT24 (all so I could run

I'd consult the KT24 technical manual to see how it works, and the
11/24 manual to see what memory cards DEC supported.  I don't remember
having any particular difficulties with configuring my 11/24 but I
wasn't doing any mixing and matching.


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