VAXen and minimal memory (was Re: The PDP11/04 has landed..)

william degnan billdegnan at
Mon Feb 8 22:11:10 CST 2016

On Mon, Feb 8, 2016 at 10:57 PM, Ethan Dicks <ethan.dicks at> wrote:

> On Mon, Feb 8, 2016 at 9:48 PM, Jon Elson <elson at> wrote:
> > On 02/08/2016 03:23 PM, Ethan Dicks wrote:
> >>
> >> I don't know if you could use the 256K boards (populated with 4116s) in
> >> the 11/730 due to the tri-voltage 4116s, but even if they worked, you
> >> wouldn't want to - 5 of them just isn't that much RAM.
> >
> > We ran our first 11/780 with 2 memory boards.  I THINK we had a total of
> 256
> > KB, and one Friday afternoon one of them died and we had to run over the
> > weekend with only one board, so that would have been 128 KB.  Yes, it
> was a
> > bit tight on memory, but we got a LOT done on that machine.
> As I mentioned our first 11/750 was delivered with 512KB (we upgraded
> it pretty quickly to 8 boards for 2MB, where it ran for years).  The
> 11/750 first shipped with IIRC VMS 2.0.  My first encounters with VMS
> was around mid-1984 and VMS 3.4.  We had 8MB of memory in our second
> 11/750 but it was supporting 50+ users.
> That 11/750 went off-lease, we sent it back.  That's why I had to
> upgrade the other one, so we'd still have an 8MB VAX in-house.  It ran
> VMS 4.7 at the end of its days 23 years ago (we had quite a bit of
> software that wasn't available for/wasn't licensed for/wasn't under
> paid-maintenance for 5.x).  I haven't powered it up since we left that
> building (I do occasionally power up the 8300 that we got for product
> development).
> So I'm fairly confident that 512MB is enough for VMS 2.0 but I _think_
> by 3.0, you had to have a megabyte or two.  1.25MB would be the most
> you could stuff in a 11/730 if you could use the boards populated with
> 16Kbit DRAMs.  I don't think VMS 2.x runs on an 11/730 (but I could be
> wrong there).  We ran Ultrix 1.1 and VMS 5.0 on one of ours (with
> 5MB).  VMS 5.0 barely fit - we mostly used that to link our product
> binaries under 5.x for distribution to our customers.
> I do know someone in Ohio who ran VMS 5.0 on a VAX-11/725, but they
> did it by cutting a slot in the skin and running a BC11 cable out to a
> BA11 box next to the 11/725 and stuffing a UDA50 in the BA11.  With an
> external disk, there's no practical difference between an 11/725 and
> an 11/730... same CPU, same backplane, same memory... just a packaging
> difference.
> -ethan

I ran my VAX 4000-200 all day today.  I have never worked with an older
VAX.  I run VMS 6.2    Today I booted off the backup drive to keep it
fresh, DIA5.  I am running MULTINET.

3 M7622 16MB RAM boards installed.  :-)

@ BillDeg:
Twitter: @billdeg <>
Youtube: @billdeg <>
Unauthorized Bio <>

More information about the cctalk mailing list